str - Rust
Description: String slices.

# Primitive Type str

1.0.0
Expand description

String slices.

See also the `std::str` module.

The `str` type, also called a ‘string slice’, is the most primitive string type. It is usually seen in its borrowed form, `&str`. It is also the type of string literals, `&'static str`.

## §Basic Usage

String literals are string slices:

    let hello_world = "Hello, World!";

Here we have declared a string slice initialized with a string literal. String literals have a static lifetime, which means the string `hello_world` is guaranteed to be valid for the duration of the entire program. We can explicitly specify `hello_world`’s lifetime as well:

    let hello_world: &'static str = "Hello, world!";

## §Representation

A `&str` is made up of two components: a pointer to some bytes, and a length. You can look at these with the `as_ptr` and `len` methods:

    use std::slice;
    use std::str;

    let story = "Once upon a time...";

    let ptr = story.as_ptr();
    let len = story.len();

    // story has nineteen bytes
    assert_eq!(19, len);

    // We can re-build a str out of ptr and len. This is all unsafe because
    // we are responsible for making sure the two components are valid:
    let s = unsafe {
        // First, we build a &[u8]...
        let slice = slice::from_raw_parts(ptr, len);

        // ... and then convert that slice into a string slice
        str::from_utf8(slice)
    };

    assert_eq!(s, Ok(story));

Note: This example shows the internals of `&str`. `unsafe` should not be used to get a string slice under normal circumstances. Use `as_str` instead.

## §Invariant

Rust libraries may assume that string slices are always valid UTF-8.

Constructing a non-UTF-8 string slice is not immediate undefined behavior, but any function called on a string slice may assume that it is valid UTF-8, which means that a non-UTF-8 string slice can lead to undefined behavior down the road.

## Implementations§

Source§

### impl str

1.0.0 (const: 1.39.0) · Source

#### pub const fn len(&self) -> usize

Returns the length of `self`.

This length is in bytes, not `char`s or graphemes. In other words, it might not be what a human considers the length of the string.

##### §Examples

    let len = "foo".len();
    assert_eq!(3, len);

    assert_eq!("ƒoo".len(), 4); // fancy f!
    assert_eq!("ƒoo".chars().count(), 3);

1.0.0 (const: 1.39.0) · Source

#### pub const fn is_empty(&self) -> bool

Returns `true` if `self` has a length of zero bytes.

##### §Examples

    let s = "";
    assert!(s.is_empty());

    let s = "not empty";
    assert!(!s.is_empty());

1.87.0 (const: 1.87.0) · Source

#### pub const fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error>

Converts a slice of bytes to a string slice.

A string slice (`&str`) is made of bytes (`u8`), and a byte slice (`&[u8]`) is made of bytes, so this function converts between the two. Not all byte slices are valid string slices, however: `&str` requires that it is valid UTF-8. `from_utf8()` checks to ensure that the bytes are valid UTF-8, and then does the conversion.

If you are sure that the byte slice is valid UTF-8, and you don’t want to incur the overhead of the validity check, there is an unsafe version of this function, `from_utf8_unchecked`, which has the same behavior but skips the check.

If you need a `String` instead of a `&str`, consider `String::from_utf8`.

Because you can stack-allocate a `[u8; N]`, and you can take a `&[u8]` of it, this function is one way to have a stack-allocated string. There is an example of this in the examples section below.

##### §Errors

Returns `Err` if the slice is not UTF-8 with a description as to why the provided slice is not UTF-8.

##### §Examples

Basic usage:

    // some bytes, in a vector
    let sparkle_heart = vec![240, 159, 146, 150];

    // We can use the ? (try) operator to check if the bytes are valid
    let sparkle_heart = str::from_utf8(&sparkle_heart)?;

    assert_eq!("💖", sparkle_heart);

Incorrect bytes:

    // some invalid bytes, in a vector
    let sparkle_heart = vec![0, 159, 146, 150];

    assert!(str::from_utf8(&sparkle_heart).is_err());

See the docs for `Utf8Error` for more details on the kinds of errors that can be returned.

A “stack allocated string”:

    // some bytes, in a stack-allocated array
    let sparkle_heart = [240, 159, 146, 150];

    // We know these bytes are valid, so just use `unwrap()`.
    let sparkle_heart: &str = str::from_utf8(&sparkle_heart).unwrap();

    assert_eq!("💖", sparkle_heart);

1.87.0 (const: 1.87.0) · Source

#### pub const fn from_utf8_mut(v: &mut [u8]) -> Result<&mut str, Utf8Error>

Converts a mutable slice of bytes to a mutable string slice.

##### §Examples

Basic usage:

    // "Hello, Rust!" as a mutable vector
    let mut hellorust = vec![72, 101, 108, 108, 111, 44, 32, 82, 117, 115, 116, 33];

    // As we know these bytes are valid, we can use `unwrap()`
    let outstr = str::from_utf8_mut(&mut hellorust).unwrap();

    assert_eq!("Hello, Rust!", outstr);

Incorrect bytes:

    // Some invalid bytes in a mutable vector
    let mut invalid = vec![128, 223];

    assert!(str::from_utf8_mut(&mut invalid).is_err());

See the docs for `Utf8Error` for more details on the kinds of errors that can be returned.

1.87.0 (const: 1.87.0) · Source

#### pub const unsafe fn from_utf8_unchecked(v: &[u8]) -> &str

Converts a slice of bytes to a string slice without checking that the string contains valid UTF-8.

See the safe version, `from_utf8`, for more information.

##### §Safety

The bytes passed in must be valid UTF-8.

##### §Examples

Basic usage:

    // some bytes, in a vector
    let sparkle_heart = vec![240, 159, 146, 150];

    let sparkle_heart = unsafe {
        str::from_utf8_unchecked(&sparkle_heart)
    };

    assert_eq!("💖", sparkle_heart);

1.87.0 (const: 1.87.0) · Source

#### pub const unsafe fn from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str

Converts a slice of bytes to a string slice without checking that the string contains valid UTF-8; mutable version.

See the immutable version, `from_utf8_unchecked()` for documentation and safety requirements.

##### §Examples

Basic usage:

    let mut heart = vec![240, 159, 146, 150];
    let heart = unsafe { str::from_utf8_unchecked_mut(&mut heart) };

    assert_eq!("💖", heart);

1.9.0 (const: 1.86.0) · Source

#### pub const fn is_char_boundary(&self, index: usize) -> bool

Checks that `index`-th byte is the first byte in a UTF-8 code point sequence or the end of the string.

The start and end of the string (when `index == self.len()`) are considered to be boundaries.

Returns `false` if `index` is greater than `self.len()`.

##### §Examples

    let s = "Löwe 老虎 Léopard";
    assert!(s.is_char_boundary(0));
    // start of `老`
    assert!(s.is_char_boundary(6));
    assert!(s.is_char_boundary(s.len()));

    // second byte of `ö`
    assert!(!s.is_char_boundary(2));

    // third byte of `老`
    assert!(!s.is_char_boundary(8));

Source

#### pub fn floor_char_boundary(&self, index: usize) -> usize

🔬This is a nightly-only experimental API. (`round_char_boundary` #93743)

Finds the closest `x` not exceeding `index` where `is_char_boundary(x)` is `true`.

This method can help you truncate a string so that it’s still valid UTF-8, but doesn’t exceed a given number of bytes. Note that this is done purely at the character level and can still visually split graphemes, even though the underlying characters aren’t split. For example, the emoji 🧑‍🔬 (scientist) could be split so that the string only includes 🧑 (person) instead.

##### §Examples

    #![feature(round_char_boundary)]
    let s = "❤️🧡💛💚💙💜";
    assert_eq!(s.len(), 26);
    assert!(!s.is_char_boundary(13));

    let closest = s.floor_char_boundary(13);
    assert_eq!(closest, 10);
    assert_eq!(&s[..closest], "❤️🧡");

Source

#### pub fn ceil_char_boundary(&self, index: usize) -> usize

🔬This is a nightly-only experimental API. (`round_char_boundary` #93743)

Finds the closest `x` not below `index` where `is_char_boundary(x)` is `true`.

If `index` is greater than the length of the string, this returns the length of the string.

This method is the natural complement to `floor_char_boundary`. See that method for more details.

##### §Examples

    #![feature(round_char_boundary)]
    let s = "❤️🧡💛💚💙💜";
    assert_eq!(s.len(), 26);
    assert!(!s.is_char_boundary(13));

    let closest = s.ceil_char_boundary(13);
    assert_eq!(closest, 14);
    assert_eq!(&s[..closest], "❤️🧡💛");

1.0.0 (const: 1.39.0) · Source

#### pub const fn as_bytes(&self) -> &[u8]

Converts a string slice to a byte slice. To convert the byte slice back into a string slice, use the `from_utf8` function.

##### §Examples

    let bytes = "bors".as_bytes();
    assert_eq!(b"bors", bytes);

1.20.0 (const: 1.83.0) · Source

#### pub const unsafe fn as_bytes_mut(&mut self) -> &mut [u8]

Converts a mutable string slice to a mutable byte slice.

##### §Safety

The caller must ensure that the content of the slice is valid UTF-8 before the borrow ends and the underlying `str` is used.

Use of a `str` whose contents are not valid UTF-8 is undefined behavior.

##### §Examples

Basic usage:

    let mut s = String::from("Hello");
    let bytes = unsafe { s.as_bytes_mut() };

    assert_eq!(b"Hello", bytes);

Mutability:

    let mut s = String::from("🗻∈🌏");

    unsafe {
        let bytes = s.as_bytes_mut();

        bytes[0] = 0xF0;
        bytes[1] = 0x9F;
        bytes[2] = 0x8D;
        bytes[3] = 0x94;
    }

    assert_eq!("🍔∈🌏", s);

1.0.0 (const: 1.32.0) · Source

#### pub const fn as_ptr(&self) -> *const u8

Converts a string slice to a raw pointer.

As string slices are a slice of bytes, the raw pointer points to a `u8`. This pointer will be pointing to the first byte of the string slice.

The caller must ensure that the returned pointer is never written to. If you need to mutate the contents of the string slice, use `as_mut_ptr`.

##### §Examples

    let s = "Hello";
    let ptr = s.as_ptr();

1.36.0 (const: 1.83.0) · Source

#### pub const fn as_mut_ptr(&mut self) -> *mut u8

Converts a mutable string slice to a raw pointer.

As string slices are a slice of bytes, the raw pointer points to a `u8`. This pointer will be pointing to the first byte of the string slice.

It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.

1.20.0 · Source

#### pub fn get<I: SliceIndex<str>>(&self, i: I) -> Option<&I::Output>

Returns a subslice of `str`.

This is the non-panicking alternative to indexing the `str`. Returns `None` whenever equivalent indexing operation would panic.

##### §Examples

    let v = String::from("🗻∈🌏");

    assert_eq!(Some("🗻"), v.get(0..4));

    // indices not on UTF-8 sequence boundaries
    assert!(v.get(1..).is_none());
    assert!(v.get(..8).is_none());

    // out of bounds
    assert!(v.get(..42).is_none());

1.20.0 · Source

#### pub fn get_mut<I: SliceIndex<str>>(&mut self, i: I) -> Option<&mut I::Output>

Returns a mutable subslice of `str`.

This is the non-panicking alternative to indexing the `str`. Returns `None` whenever equivalent indexing operation would panic.

##### §Examples

    let mut v = String::from("hello");
    // correct length
    assert!(v.get_mut(0..5).is_some());
    // out of bounds
    assert!(v.get_mut(..42).is_none());
    assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));

    assert_eq!("hello", v);
    {
        let s = v.get_mut(0..2);
        let s = s.map(|s| {
            s.make_ascii_uppercase();
            &*s
        });
        assert_eq!(Some("HE"), s);
    }
    assert_eq!("HEllo", v);

1.20.0 · Source

#### pub unsafe fn get_unchecked<I: SliceIndex<str>>(&self, i: I) -> &I::Output

Returns an unchecked subslice of `str`.

This is the unchecked alternative to indexing the `str`.

##### §Safety

Callers of this function are responsible that these preconditions are satisfied:

- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.

Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the `str` type.

##### §Examples

    let v = "🗻∈🌏";
    unsafe {
        assert_eq!("🗻", v.get_unchecked(0..4));
        assert_eq!("∈", v.get_unchecked(4..7));
        assert_eq!("🌏", v.get_unchecked(7..11));
    }

1.20.0 · Source

#### pub unsafe fn get_unchecked_mut<I: SliceIndex<str>>( &mut self, i: I, ) -> &mut I::Output

Returns a mutable, unchecked subslice of `str`.

This is the unchecked alternative to indexing the `str`.

##### §Safety

Callers of this function are responsible that these preconditions are satisfied:

- The starting index must not exceed the ending index;
- Indexes must be within bounds of the original slice;
- Indexes must lie on UTF-8 sequence boundaries.

Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the `str` type.

##### §Examples

    let mut v = String::from("🗻∈🌏");
    unsafe {
        assert_eq!("🗻", v.get_unchecked_mut(0..4));
        assert_eq!("∈", v.get_unchecked_mut(4..7));
        assert_eq!("🌏", v.get_unchecked_mut(7..11));
    }

1.0.0 · Source

#### pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str

👎Deprecated since 1.29.0: use `get_unchecked(begin..end)` instead

Creates a string slice from another string slice, bypassing safety checks.

This is generally not recommended, use with caution! For a safe alternative see `str` and `Index`.

This new slice goes from `begin` to `end`, including `begin` but excluding `end`.

To get a mutable string slice instead, see the `slice_mut_unchecked` method.

##### §Safety

Callers of this function are responsible that three preconditions are satisfied:

- `begin` must not exceed `end`.
- `begin` and `end` must be byte positions within the string slice.
- `begin` and `end` must lie on UTF-8 sequence boundaries.

##### §Examples

    let s = "Löwe 老虎 Léopard";

    unsafe {
        assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
    }

    let s = "Hello, world!";

    unsafe {
        assert_eq!("world", s.slice_unchecked(7, 12));
    }

1.5.0 · Source

#### pub unsafe fn slice_mut_unchecked( &mut self, begin: usize, end: usize, ) -> &mut str

👎Deprecated since 1.29.0: use `get_unchecked_mut(begin..end)` instead

Creates a string slice from another string slice, bypassing safety checks.

This is generally not recommended, use with caution! For a safe alternative see `str` and `IndexMut`.

This new slice goes from `begin` to `end`, including `begin` but excluding `end`.

To get an immutable string slice instead, see the `slice_unchecked` method.

##### §Safety

Callers of this function are responsible that three preconditions are satisfied:

- `begin` must not exceed `end`.
- `begin` and `end` must be byte positions within the string slice.
- `begin` and `end` must lie on UTF-8 sequence boundaries.

1.4.0 (const: 1.86.0) · Source

#### pub const fn split_at(&self, mid: usize) -> (&str, &str)

Divides one string slice into two at an index.

The argument, `mid`, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to `mid`, and from `mid` to the end of the string slice.

To get mutable string slices instead, see the `split_at_mut` method.

##### §Panics

Panics if `mid` is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice. For a non-panicking alternative see `split_at_checked`.

##### §Examples

    let s = "Per Martin-Löf";

    let (first, last) = s.split_at(3);

    assert_eq!("Per", first);
    assert_eq!(" Martin-Löf", last);

1.4.0 (const: 1.86.0) · Source

#### pub const fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)

Divides one mutable string slice into two at an index.

The argument, `mid`, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to `mid`, and from `mid` to the end of the string slice.

To get immutable string slices instead, see the `split_at` method.

##### §Panics

Panics if `mid` is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice. For a non-panicking alternative see `split_at_mut_checked`.

##### §Examples

    let mut s = "Per Martin-Löf".to_string();
    {
        let (first, last) = s.split_at_mut(3);
        first.make_ascii_uppercase();
        assert_eq!("PER", first);
        assert_eq!(" Martin-Löf", last);
    }
    assert_eq!("PER Martin-Löf", s);

1.80.0 (const: 1.86.0) · Source

#### pub const fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>

Divides one string slice into two at an index.

The argument, `mid`, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns `None` if that’s not the case.

The two slices returned go from the start of the string slice to `mid`, and from `mid` to the end of the string slice.

To get mutable string slices instead, see the `split_at_mut_checked` method.

##### §Examples

    let s = "Per Martin-Löf";

    let (first, last) = s.split_at_checked(3).unwrap();
    assert_eq!("Per", first);
    assert_eq!(" Martin-Löf", last);

    assert_eq!(None, s.split_at_checked(13));  // Inside “ö”
    assert_eq!(None, s.split_at_checked(16));  // Beyond the string length

1.80.0 (const: 1.86.0) · Source

#### pub const fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut str, &mut str)>

Divides one mutable string slice into two at an index.

The argument, `mid`, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns `None` if that’s not the case.

The two slices returned go from the start of the string slice to `mid`, and from `mid` to the end of the string slice.

To get immutable string slices instead, see the `split_at_checked` method.

##### §Examples

    let mut s = "Per Martin-Löf".to_string();
    if let Some((first, last)) = s.split_at_mut_checked(3) {
        first.make_ascii_uppercase();
        assert_eq!("PER", first);
        assert_eq!(" Martin-Löf", last);
    }
    assert_eq!("PER Martin-Löf", s);

    assert_eq!(None, s.split_at_mut_checked(13));  // Inside “ö”
    assert_eq!(None, s.split_at_mut_checked(16));  // Beyond the string length

1.0.0 · Source

#### pub fn chars(&self) -> Chars<'_> ⓘ

Returns an iterator over the `char`s of a string slice.

As a string slice consists of valid UTF-8, we can iterate through a string slice by `char`. This method returns such an iterator.

It’s important to remember that `char` represents a Unicode Scalar Value, and might not match your idea of what a ‘character’ is. Iteration over grapheme clusters may be what you actually want. This functionality is not provided by Rust’s standard library, check crates.io instead.

##### §Examples

Basic usage:

    let word = "goodbye";

    let count = word.chars().count();
    assert_eq!(7, count);

    let mut chars = word.chars();

    assert_eq!(Some('g'), chars.next());
    assert_eq!(Some('o'), chars.next());
    assert_eq!(Some('o'), chars.next());
    assert_eq!(Some('d'), chars.next());
    assert_eq!(Some('b'), chars.next());
    assert_eq!(Some('y'), chars.next());
    assert_eq!(Some('e'), chars.next());

    assert_eq!(None, chars.next());

Remember, `char`s might not match your intuition about characters:

    let y = "y̆";

    let mut chars = y.chars();

    assert_eq!(Some('y'), chars.next()); // not 'y̆'
    assert_eq!(Some('\u{0306}'), chars.next());

    assert_eq!(None, chars.next());

1.0.0 · Source

#### pub fn char_indices(&self) -> CharIndices<'_> ⓘ

Returns an iterator over the `char`s of a string slice, and their positions.

As a string slice consists of valid UTF-8, we can iterate through a string slice by `char`. This method returns an iterator of both these `char`s, as well as their byte positions.

The iterator yields tuples. The position is first, the `char` is second.

##### §Examples

Basic usage:

    let word = "goodbye";

    let count = word.char_indices().count();
    assert_eq!(7, count);

    let mut char_indices = word.char_indices();

    assert_eq!(Some((0, 'g')), char_indices.next());
    assert_eq!(Some((1, 'o')), char_indices.next());
    assert_eq!(Some((2, 'o')), char_indices.next());
    assert_eq!(Some((3, 'd')), char_indices.next());
    assert_eq!(Some((4, 'b')), char_indices.next());
    assert_eq!(Some((5, 'y')), char_indices.next());
    assert_eq!(Some((6, 'e')), char_indices.next());

    assert_eq!(None, char_indices.next());

Remember, `char`s might not match your intuition about characters:

    let yes = "y̆es";

    let mut char_indices = yes.char_indices();

    assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
    assert_eq!(Some((1, '\u{0306}')), char_indices.next());

    // note the 3 here - the previous character took up two bytes
    assert_eq!(Some((3, 'e')), char_indices.next());
    assert_eq!(Some((4, 's')), char_indices.next());

    assert_eq!(None, char_indices.next());

1.0.0 · Source

#### pub fn bytes(&self) -> Bytes<'_> ⓘ

Returns an iterator over the bytes of a string slice.

As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.

##### §Examples

    let mut bytes = "bors".bytes();

    assert_eq!(Some(b'b'), bytes.next());
    assert_eq!(Some(b'o'), bytes.next());
    assert_eq!(Some(b'r'), bytes.next());
    assert_eq!(Some(b's'), bytes.next());

    assert_eq!(None, bytes.next());

1.1.0 · Source

#### pub fn split_whitespace(&self) -> SplitWhitespace<'_> ⓘ

Splits a string slice by whitespace.

The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of whitespace.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`. If you only want to split on ASCII whitespace instead, use `split_ascii_whitespace`.

##### §Examples

Basic usage:

    let mut iter = "A few words".split_whitespace();

    assert_eq!(Some("A"), iter.next());
    assert_eq!(Some("few"), iter.next());
    assert_eq!(Some("words"), iter.next());

    assert_eq!(None, iter.next());

All kinds of whitespace are considered:

    let mut iter = " Mary   had\ta\u{2009}little  \n\t lamb".split_whitespace();
    assert_eq!(Some("Mary"), iter.next());
    assert_eq!(Some("had"), iter.next());
    assert_eq!(Some("a"), iter.next());
    assert_eq!(Some("little"), iter.next());
    assert_eq!(Some("lamb"), iter.next());

    assert_eq!(None, iter.next());

If the string is empty or all whitespace, the iterator yields no string slices:

    assert_eq!("".split_whitespace().next(), None);
    assert_eq!("   ".split_whitespace().next(), None);

1.34.0 · Source

#### pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_> ⓘ

Splits a string slice by ASCII whitespace.

The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of ASCII whitespace.

To split by Unicode `Whitespace` instead, use `split_whitespace`.

##### §Examples

Basic usage:

    let mut iter = "A few words".split_ascii_whitespace();

    assert_eq!(Some("A"), iter.next());
    assert_eq!(Some("few"), iter.next());
    assert_eq!(Some("words"), iter.next());

    assert_eq!(None, iter.next());

All kinds of ASCII whitespace are considered:

    let mut iter = " Mary   had\ta little  \n\t lamb".split_ascii_whitespace();
    assert_eq!(Some("Mary"), iter.next());
    assert_eq!(Some("had"), iter.next());
    assert_eq!(Some("a"), iter.next());
    assert_eq!(Some("little"), iter.next());
    assert_eq!(Some("lamb"), iter.next());

    assert_eq!(None, iter.next());

If the string is empty or all ASCII whitespace, the iterator yields no string slices:

    assert_eq!("".split_ascii_whitespace().next(), None);
    assert_eq!("   ".split_ascii_whitespace().next(), None);

1.0.0 · Source

#### pub fn lines(&self) -> Lines<'_> ⓘ

Returns an iterator over the lines of a string, as string slices.

Lines are split at line endings that are either newlines (`\n`) or sequences of a carriage return followed by a line feed (`\r\n`).

Line terminators are not included in the lines returned by the iterator.

Note that any carriage return (`\r`) not immediately followed by a line feed (`\n`) does not split a line. These carriage returns are thereby included in the produced lines.

The final line ending is optional. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.

##### §Examples

Basic usage:

    let text = "foo\r\nbar\n\nbaz\r";
    let mut lines = text.lines();

    assert_eq!(Some("foo"), lines.next());
    assert_eq!(Some("bar"), lines.next());
    assert_eq!(Some(""), lines.next());
    // Trailing carriage return is included in the last line
    assert_eq!(Some("baz\r"), lines.next());

    assert_eq!(None, lines.next());

The final line does not require any ending:

    let text = "foo\nbar\n\r\nbaz";
    let mut lines = text.lines();

    assert_eq!(Some("foo"), lines.next());
    assert_eq!(Some("bar"), lines.next());
    assert_eq!(Some(""), lines.next());
    assert_eq!(Some("baz"), lines.next());

    assert_eq!(None, lines.next());

1.0.0 · Source

#### pub fn lines_any(&self) -> LinesAny<'_> ⓘ

👎Deprecated since 1.4.0: use lines() instead now

Returns an iterator over the lines of a string.

1.8.0 · Source

#### pub fn encode_utf16(&self) -> EncodeUtf16<'_> ⓘ

Returns an iterator of `u16` over the string encoded as native endian UTF-16 (without byte-order mark).

##### §Examples

    let text = "Zażółć gęślą jaźń";

    let utf8_len = text.len();
    let utf16_len = text.encode_utf16().count();

    assert!(utf16_len <= utf8_len);

1.0.0 · Source

#### pub fn contains<P: Pattern>(&self, pat: P) -> bool

Returns `true` if the given pattern matches a sub-slice of this string slice.

Returns `false` if it does not.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

    let bananas = "bananas";

    assert!(bananas.contains("nana"));
    assert!(!bananas.contains("apples"));

1.0.0 · Source

#### pub fn starts_with<P: Pattern>(&self, pat: P) -> bool

Returns `true` if the given pattern matches a prefix of this string slice.

Returns `false` if it does not.

The pattern can be a `&str`, in which case this function will return true if the `&str` is a prefix of this string slice.

The pattern can also be a `char`, a slice of `char`s, or a function or closure that determines if a character matches. These will only be checked against the first character of this string slice. Look at the second example below regarding behavior for slices of `char`s.

##### §Examples

    let bananas = "bananas";

    assert!(bananas.starts_with("bana"));
    assert!(!bananas.starts_with("nana"));

    let bananas = "bananas";

    // Note that both of these assert successfully.
    assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
    assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));

1.0.0 · Source

#### pub fn ends_with<P: Pattern>(&self, pat: P) -> bool
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns `true` if the given pattern matches a suffix of this string slice.

Returns `false` if it does not.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

    let bananas = "bananas";

    assert!(bananas.ends_with("anas"));
    assert!(!bananas.ends_with("nana"));

1.0.0 · Source

#### pub fn find<P: Pattern>(&self, pat: P) -> Option<usize>

Returns the byte index of the first character of this string slice that matches the pattern.

Returns `None` if the pattern doesn’t match.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

Simple patterns:

    let s = "Löwe 老虎 Léopard Gepardi";

    assert_eq!(s.find('L'), Some(0));
    assert_eq!(s.find('é'), Some(14));
    assert_eq!(s.find("pard"), Some(17));

More complex patterns using point-free style and closures:

    let s = "Löwe 老虎 Léopard";

    assert_eq!(s.find(char::is_whitespace), Some(5));
    assert_eq!(s.find(char::is_lowercase), Some(1));
    assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
    assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));

Not finding the pattern:

    let s = "Löwe 老虎 Léopard";
    let x: &[_] = &['1', '2'];

    assert_eq!(s.find(x), None);

1.0.0 · Source

#### pub fn rfind<P: Pattern>(&self, pat: P) -> Option<usize>
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns the byte index for the first character of the last match of the pattern in this string slice.

Returns `None` if the pattern doesn’t match.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

Simple patterns:

    let s = "Löwe 老虎 Léopard Gepardi";

    assert_eq!(s.rfind('L'), Some(13));
    assert_eq!(s.rfind('é'), Some(14));
    assert_eq!(s.rfind("pard"), Some(24));

More complex patterns with closures:

    let s = "Löwe 老虎 Léopard";

    assert_eq!(s.rfind(char::is_whitespace), Some(12));
    assert_eq!(s.rfind(char::is_lowercase), Some(20));

Not finding the pattern:

    let s = "Löwe 老虎 Léopard";
    let x: &[_] = &['1', '2'];

    assert_eq!(s.rfind(x), None);

1.0.0 · Source

#### pub fn split<P: Pattern>(&self, pat: P) -> Split<'_, P> ⓘ

Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator will be a `DoubleEndedIterator` if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., `char`, but not for `&str`.

If the pattern allows a reverse search but its results might differ from a forward search, the `rsplit` method can be used.

##### §Examples

Simple patterns:

    let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
    assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);

    let v: Vec<&str> = "".split('X').collect();
    assert_eq!(v, [""]);

    let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
    assert_eq!(v, ["lion", "", "tiger", "leopard"]);

    let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
    assert_eq!(v, ["lion", "tiger", "leopard"]);

    let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
    assert_eq!(v, ["abc", "def", "ghi"]);

    let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
    assert_eq!(v, ["lion", "tiger", "leopard"]);

If the pattern is a slice of chars, split on each occurrence of any of the characters:

    let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
    assert_eq!(v, ["2020", "11", "03", "23", "59"]);

A more complex pattern, using a closure:

    let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
    assert_eq!(v, ["abc", "def", "ghi"]);

If a string contains multiple contiguous separators, you will end up with empty strings in the output:

    let x = "||||a||b|c".to_string();
    let d: Vec<_> = x.split('|').collect();

    assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

Contiguous separators are separated by the empty string.

    let x = "(///)".to_string();
    let d: Vec<_> = x.split('/').collect();

    assert_eq!(d, &["(", "", "", ")"]);

Separators at the start or end of a string are neighbored by empty strings.

    let d: Vec<_> = "010".split("0").collect();
    assert_eq!(d, &["", "1", ""]);

When the empty string is used as a separator, it separates every character in the string, along with the beginning and end of the string.

    let f: Vec<_> = "rust".split("").collect();
    assert_eq!(f, &["", "r", "u", "s", "t", ""]);

Contiguous separators can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:

    let x = "    a  b c".to_string();
    let d: Vec<_> = x.split(' ').collect();

    assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

It does not give you:

ⓘ

    assert_eq!(d, &["a", "b", "c"]);

Use `split_whitespace` for this behavior.

1.51.0 · Source

#### pub fn split_inclusive<P: Pattern>(&self, pat: P) -> SplitInclusive<'_, P> ⓘ

Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.

Differs from the iterator produced by `split` in that `split_inclusive` leaves the matched part as the terminator of the substring.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

    let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
        .split_inclusive('\n').collect();
    assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);

If the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.

    let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
        .split_inclusive('\n').collect();
    assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);

1.0.0 · Source

#### pub fn rsplit<P: Pattern>(&self, pat: P) -> RSplit<'_, P> ⓘ
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a `DoubleEndedIterator` if a forward/reverse search yields the same elements.

For iterating from the front, the `split` method can be used.

##### §Examples

Simple patterns:

    let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
    assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);

    let v: Vec<&str> = "".rsplit('X').collect();
    assert_eq!(v, [""]);

    let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
    assert_eq!(v, ["leopard", "tiger", "", "lion"]);

    let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
    assert_eq!(v, ["leopard", "tiger", "lion"]);

A more complex pattern, using a closure:

    let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
    assert_eq!(v, ["ghi", "def", "abc"]);

1.0.0 · Source

#### pub fn split_terminator<P: Pattern>(&self, pat: P) -> SplitTerminator<'_, P> ⓘ

Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

Equivalent to `split`, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

##### §Iterator behavior

The returned iterator will be a `DoubleEndedIterator` if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., `char`, but not for `&str`.

If the pattern allows a reverse search but its results might differ from a forward search, the `rsplit_terminator` method can be used.

##### §Examples

    let v: Vec<&str> = "A.B.".split_terminator('.').collect();
    assert_eq!(v, ["A", "B"]);

    let v: Vec<&str> = "A..B..".split_terminator(".").collect();
    assert_eq!(v, ["A", "", "B", ""]);

    let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
    assert_eq!(v, ["A", "B", "C", "D"]);

1.0.0 · Source

#### pub fn rsplit_terminator<P: Pattern>(&self, pat: P) -> RSplitTerminator<'_, P> ⓘ
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns an iterator over substrings of `self`, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

Equivalent to `split`, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

##### §Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.

For iterating from the front, the `split_terminator` method can be used.

##### §Examples

    let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
    assert_eq!(v, ["B", "A"]);

    let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
    assert_eq!(v, ["", "B", "", "A"]);

    let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
    assert_eq!(v, ["D", "C", "B", "A"]);

1.0.0 · Source

#### pub fn splitn<P: Pattern>(&self, n: usize, pat: P) -> SplitN<'_, P> ⓘ

Returns an iterator over substrings of the given string slice, separated by a pattern, restricted to returning at most `n` items.

If `n` substrings are returned, the last substring (the `n`th substring) will contain the remainder of the string.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

If the pattern allows a reverse search, the `rsplitn` method can be used.

##### §Examples

Simple patterns:

    let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
    assert_eq!(v, ["Mary", "had", "a little lambda"]);

    let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
    assert_eq!(v, ["lion", "", "tigerXleopard"]);

    let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
    assert_eq!(v, ["abcXdef"]);

    let v: Vec<&str> = "".splitn(1, 'X').collect();
    assert_eq!(v, [""]);

A more complex pattern, using a closure:

    let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
    assert_eq!(v, ["abc", "defXghi"]);

1.0.0 · Source

#### pub fn rsplitn<P: Pattern>(&self, n: usize, pat: P) -> RSplitN<'_, P> ⓘ
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns an iterator over substrings of this string slice, separated by a pattern, starting from the end of the string, restricted to returning at most `n` items.

If `n` substrings are returned, the last substring (the `n`th substring) will contain the remainder of the string.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

For splitting from the front, the `splitn` method can be used.

##### §Examples

Simple patterns:

    let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
    assert_eq!(v, ["lamb", "little", "Mary had a"]);

    let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
    assert_eq!(v, ["leopard", "tiger", "lionX"]);

    let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
    assert_eq!(v, ["leopard", "lion::tiger"]);

A more complex pattern, using a closure:

    let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
    assert_eq!(v, ["ghi", "abc1def"]);

1.52.0 · Source

#### pub fn split_once<P: Pattern>(&self, delimiter: P) -> Option<(&str, &str)>

Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

##### §Examples

    assert_eq!("cfg".split_once('='), None);
    assert_eq!("cfg=".split_once('='), Some(("cfg", "")));
    assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
    assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));

1.52.0 · Source

#### pub fn rsplit_once<P: Pattern>(&self, delimiter: P) -> Option<(&str, &str)>
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

##### §Examples

    assert_eq!("cfg".rsplit_once('='), None);
    assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
    assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));

1.2.0 · Source

#### pub fn matches<P: Pattern>(&self, pat: P) -> Matches<'_, P> ⓘ

Returns an iterator over the disjoint matches of a pattern within the given string slice.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator will be a `DoubleEndedIterator` if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., `char`, but not for `&str`.

If the pattern allows a reverse search but its results might differ from a forward search, the `rmatches` method can be used.

##### §Examples

    let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
    assert_eq!(v, ["abc", "abc", "abc"]);

    let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
    assert_eq!(v, ["1", "2", "3"]);

1.2.0 · Source

#### pub fn rmatches<P: Pattern>(&self, pat: P) -> RMatches<'_, P> ⓘ
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns an iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a `DoubleEndedIterator` if a forward/reverse search yields the same elements.

For iterating from the front, the `matches` method can be used.

##### §Examples

    let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
    assert_eq!(v, ["abc", "abc", "abc"]);

    let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
    assert_eq!(v, ["3", "2", "1"]);

1.5.0 · Source

#### pub fn match_indices<P: Pattern>(&self, pat: P) -> MatchIndices<'_, P> ⓘ

Returns an iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.

For matches of `pat` within `self` that overlap, only the indices corresponding to the first match are returned.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator will be a `DoubleEndedIterator` if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., `char`, but not for `&str`.

If the pattern allows a reverse search but its results might differ from a forward search, the `rmatch_indices` method can be used.

##### §Examples

    let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
    assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);

    let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
    assert_eq!(v, [(1, "abc"), (4, "abc")]);

    let v: Vec<_> = "ababa".match_indices("aba").collect();
    assert_eq!(v, [(0, "aba")]); // only the first `aba`

1.5.0 · Source

#### pub fn rmatch_indices<P: Pattern>(&self, pat: P) -> RMatchIndices<'_, P> ⓘ
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns an iterator over the disjoint matches of a pattern within `self`, yielded in reverse order along with the index of the match.

For matches of `pat` within `self` that overlap, only the indices corresponding to the last match are returned.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a `DoubleEndedIterator` if a forward/reverse search yields the same elements.

For iterating from the front, the `match_indices` method can be used.

##### §Examples

    let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
    assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);

    let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
    assert_eq!(v, [(4, "abc"), (1, "abc")]);

    let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
    assert_eq!(v, [(2, "aba")]); // only the last `aba`

1.0.0 · Source

#### pub fn trim(&self) -> &str

Returns a string slice with leading and trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`, which includes newlines.

##### §Examples

    let s = "\n Hello\tworld\t\n";

    assert_eq!("Hello\tworld", s.trim());

1.30.0 · Source

#### pub fn trim_start(&self) -> &str

Returns a string slice with leading whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`, which includes newlines.

##### §Text directionality

A string is a sequence of bytes. `start` in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.

##### §Examples

Basic usage:

    let s = "\n Hello\tworld\t\n";
    assert_eq!("Hello\tworld\t\n", s.trim_start());

Directionality:

    let s = "  English  ";
    assert!(Some('E') == s.trim_start().chars().next());

    let s = "  עברית  ";
    assert!(Some('ע') == s.trim_start().chars().next());

1.30.0 · Source

#### pub fn trim_end(&self) -> &str

Returns a string slice with trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`, which includes newlines.

##### §Text directionality

A string is a sequence of bytes. `end` in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.

##### §Examples

Basic usage:

    let s = "\n Hello\tworld\t\n";
    assert_eq!("\n Hello\tworld", s.trim_end());

Directionality:

    let s = "  English  ";
    assert!(Some('h') == s.trim_end().chars().rev().next());

    let s = "  עברית  ";
    assert!(Some('ת') == s.trim_end().chars().rev().next());

1.0.0 · Source

#### pub fn trim_left(&self) -> &str

👎Deprecated since 1.33.0: superseded by `trim_start`

Returns a string slice with leading whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`.

##### §Text directionality

A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.

##### §Examples

Basic usage:

    let s = " Hello\tworld\t";

    assert_eq!("Hello\tworld\t", s.trim_left());

Directionality:

    let s = "  English";
    assert!(Some('E') == s.trim_left().chars().next());

    let s = "  עברית";
    assert!(Some('ע') == s.trim_left().chars().next());

1.0.0 · Source

#### pub fn trim_right(&self) -> &str

👎Deprecated since 1.33.0: superseded by `trim_end`

Returns a string slice with trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property `White_Space`.

##### §Text directionality

A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.

##### §Examples

Basic usage:

    let s = " Hello\tworld\t";

    assert_eq!(" Hello\tworld", s.trim_right());

Directionality:

    let s = "English  ";
    assert!(Some('h') == s.trim_right().chars().rev().next());

    let s = "עברית  ";
    assert!(Some('ת') == s.trim_right().chars().rev().next());

1.0.0 · Source

#### pub fn trim_matches<P: Pattern>(&self, pat: P) -> &str
where for<'a> P::Searcher<'a>: DoubleEndedSearcher<'a>,

Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.

The pattern can be a `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

Simple patterns:

    assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
    assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");

    let x: &[_] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");

A more complex pattern, using a closure:

    assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");

1.30.0 · Source

#### pub fn trim_start_matches<P: Pattern>(&self, pat: P) -> &str

Returns a string slice with all prefixes that match a pattern repeatedly removed.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Text directionality

A string is a sequence of bytes. `start` in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.

##### §Examples

    assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
    assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");

    let x: &[_] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");

1.45.0 · Source

#### pub fn strip_prefix<P: Pattern>(&self, prefix: P) -> Option<&str>

Returns a string slice with the prefix removed.

If the string starts with the pattern `prefix`, returns the substring after the prefix, wrapped in `Some`. Unlike `trim_start_matches`, this method removes the prefix exactly once.

If the string does not start with `prefix`, returns `None`.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

    assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
    assert_eq!("foo:bar".strip_prefix("bar"), None);
    assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));

1.45.0 · Source

#### pub fn strip_suffix<P: Pattern>(&self, suffix: P) -> Option<&str>
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns a string slice with the suffix removed.

If the string ends with the pattern `suffix`, returns the substring before the suffix, wrapped in `Some`. Unlike `trim_end_matches`, this method removes the suffix exactly once.

If the string does not end with `suffix`, returns `None`.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Examples

    assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
    assert_eq!("bar:foo".strip_suffix("bar"), None);
    assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));

1.30.0 · Source

#### pub fn trim_end_matches<P: Pattern>(&self, pat: P) -> &str
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

Returns a string slice with all suffixes that match a pattern repeatedly removed.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Text directionality

A string is a sequence of bytes. `end` in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.

##### §Examples

Simple patterns:

    assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
    assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");

    let x: &[_] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");

A more complex pattern, using a closure:

    assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");

1.0.0 · Source

#### pub fn trim_left_matches<P: Pattern>(&self, pat: P) -> &str

👎Deprecated since 1.33.0: superseded by `trim_start_matches`

Returns a string slice with all prefixes that match a pattern repeatedly removed.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Text directionality

A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.

##### §Examples

    assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
    assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");

    let x: &[_] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");

1.0.0 · Source

#### pub fn trim_right_matches<P: Pattern>(&self, pat: P) -> &str
where for<'a> P::Searcher<'a>: ReverseSearcher<'a>,

👎Deprecated since 1.33.0: superseded by `trim_end_matches`

Returns a string slice with all suffixes that match a pattern repeatedly removed.

The pattern can be a `&str`, `char`, a slice of `char`s, or a function or closure that determines if a character matches.

##### §Text directionality

A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.

##### §Examples

Simple patterns:

    assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
    assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");

    let x: &[_] = &['1', '2'];
    assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");

A more complex pattern, using a closure:

    assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");

1.0.0 · Source

#### pub fn parse<F: FromStr>(&self) -> Result<F, F::Err>

Parses this string slice into another type.

Because `parse` is so general, it can cause problems with type inference. As such, `parse` is one of the few times you’ll see the syntax affectionately known as the ‘turbofish’: `::<>`. This helps the inference algorithm understand specifically which type you’re trying to parse into.

`parse` can parse into any type that implements the `FromStr` trait.

##### §Errors

Will return `Err` if it’s not possible to parse this string slice into the desired type.

##### §Examples

Basic usage:

    let four: u32 = "4".parse().unwrap();

    assert_eq!(4, four);

Using the ‘turbofish’ instead of annotating `four`:

    let four = "4".parse::<u32>();

    assert_eq!(Ok(4), four);

Failing to parse:

    let nope = "j".parse::<u32>();

    assert!(nope.is_err());

1.23.0 (const: 1.74.0) · Source

#### pub const fn is_ascii(&self) -> bool

Checks if all characters in this string are within the ASCII range.

##### §Examples

    let ascii = "hello!\n";
    let non_ascii = "Grüße, Jürgen ❤";

    assert!(ascii.is_ascii());
    assert!(!non_ascii.is_ascii());

Source

#### pub const fn as_ascii(&self) -> Option<&[Char]>

🔬This is a nightly-only experimental API. (`ascii_char` #110998)

If this string slice `is_ascii`, returns it as a slice of ASCII characters, otherwise returns `None`.

1.23.0 (const: unstable) · Source

#### pub fn eq_ignore_ascii_case(&self, other: &str) -> bool

Checks that two strings are an ASCII case-insensitive match.

Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`, but without allocating and copying temporaries.

##### §Examples

    assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
    assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
    assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));

1.23.0 (const: 1.84.0) · Source

#### pub const fn make_ascii_uppercase(&mut self)

Converts this string to its ASCII upper case equivalent in-place.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use `to_ascii_uppercase()`.

##### §Examples

    let mut s = String::from("Grüße, Jürgen ❤");

    s.make_ascii_uppercase();

    assert_eq!("GRüßE, JüRGEN ❤", s);

1.23.0 (const: 1.84.0) · Source

#### pub const fn make_ascii_lowercase(&mut self)

Converts this string to its ASCII lower case equivalent in-place.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use `to_ascii_lowercase()`.

##### §Examples

    let mut s = String::from("GRÜßE, JÜRGEN ❤");

    s.make_ascii_lowercase();

    assert_eq!("grÜße, jÜrgen ❤", s);

1.80.0 (const: 1.80.0) · Source

#### pub const fn trim_ascii_start(&self) -> &str

Returns a string slice with leading ASCII whitespace removed.

‘Whitespace’ refers to the definition used by `u8::is_ascii_whitespace`.

##### §Examples

    assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
    assert_eq!("  ".trim_ascii_start(), "");
    assert_eq!("".trim_ascii_start(), "");

1.80.0 (const: 1.80.0) · Source

#### pub const fn trim_ascii_end(&self) -> &str

Returns a string slice with trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by `u8::is_ascii_whitespace`.

##### §Examples

    assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
    assert_eq!("  ".trim_ascii_end(), "");
    assert_eq!("".trim_ascii_end(), "");

1.80.0 (const: 1.80.0) · Source

#### pub const fn trim_ascii(&self) -> &str

Returns a string slice with leading and trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by `u8::is_ascii_whitespace`.

##### §Examples

    assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
    assert_eq!("  ".trim_ascii(), "");
    assert_eq!("".trim_ascii(), "");

1.34.0 · Source

#### pub fn escape_debug(&self) -> EscapeDebug<'_> ⓘ

Returns an iterator that escapes each char in `self` with `char::escape_debug`.

Note: only extended grapheme codepoints that begin the string will be escaped.

##### §Examples

As an iterator:

    for c in "❤\n!".escape_debug() {
        print!("{c}");
    }
    println!();

Using `println!` directly:

    println!("{}", "❤\n!".escape_debug());

Both are equivalent to:

    println!("❤\\n!");

Using `to_string`:

    assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");

1.34.0 · Source

#### pub fn escape_default(&self) -> EscapeDefault<'_> ⓘ

Returns an iterator that escapes each char in `self` with `char::escape_default`.

##### §Examples

As an iterator:

    for c in "❤\n!".escape_default() {
        print!("{c}");
    }
    println!();

Using `println!` directly:

    println!("{}", "❤\n!".escape_default());

Both are equivalent to:

    println!("\\u{{2764}}\\n!");

Using `to_string`:

    assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");

1.34.0 · Source

#### pub fn escape_unicode(&self) -> EscapeUnicode<'_> ⓘ

Returns an iterator that escapes each char in `self` with `char::escape_unicode`.

##### §Examples

As an iterator:

    for c in "❤\n!".escape_unicode() {
        print!("{c}");
    }
    println!();

Using `println!` directly:

    println!("{}", "❤\n!".escape_unicode());

Both are equivalent to:

    println!("\\u{{2764}}\\u{{a}}\\u{{21}}");

Using `to_string`:

    assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");

Source

#### pub fn substr_range(&self, substr: &str) -> Option<Range<usize>>

🔬This is a nightly-only experimental API. (`substr_range` #126769)

Returns the range that a substring points to.

Returns `None` if `substr` does not point within `self`.

Unlike `str::find`, this does not search through the string. Instead, it uses pointer arithmetic to find where in the string `substr` is derived from.

This is useful for extending `str::split` and similar methods.

Note that this method may return false positives (typically either `Some(0..0)` or `Some(self.len()..self.len())`) if `substr` is a zero-length `str` that points at the beginning or end of another, independent, `str`.

##### §Examples

    #![feature(substr_range)]

    let data = "a, b, b, a";
    let mut iter = data.split(", ").map(|s| data.substr_range(s).unwrap());

    assert_eq!(iter.next(), Some(0..1));
    assert_eq!(iter.next(), Some(3..4));
    assert_eq!(iter.next(), Some(6..7));
    assert_eq!(iter.next(), Some(9..10));

Source

#### pub fn as_str(&self) -> &str

🔬This is a nightly-only experimental API. (`str_as_str` #130366)

Returns the same string as a string slice `&str`.

This method is redundant when used directly on `&str`, but it helps dereferencing other string-like types to string slices, for example references to `Box<str>` or `Arc<str>`.

## Trait Implementations§

1.51.0 · Source§

### impl AsMut<str> for str

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#### fn as_mut(&mut self) -> &mut str

Converts this type into a mutable reference of the (usually inferred) input type.
1.0.0 · Source§

### impl AsRef<[u8]> for str

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#### fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.
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### impl AsRef<ByteStr> for str

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#### fn as_ref(&self) -> &ByteStr

Converts this type into a shared reference of the (usually inferred) input type.
1.0.0 · Source§

### impl AsRef<str> for str

Source§

#### fn as_ref(&self) -> &str

Converts this type into a shared reference of the (usually inferred) input type.
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### impl CloneToUninit for str

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#### unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (`clone_to_uninit` #126799)
Performs copy-assignment from `self` to `dest`. Read more
1.0.0 · Source§

### impl Debug for str

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
1.28.0 · Source§

### impl Default for &mut str

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#### fn default() -> Self

Creates an empty mutable str

1.0.0 · Source§

### impl Default for &str

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#### fn default() -> Self

Creates an empty str

1.0.0 · Source§

### impl Display for str

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
1.0.0 · Source§

### impl Hash for str

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#### fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given `Hasher`. Read more
1.0.0 · Source§

### impl<I> Index<I> for str
where I: SliceIndex<str>,

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#### type Output = <I as SliceIndex<str>>::Output

The returned type after indexing.
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#### fn index(&self, index: I) -> &I::Output

Performs the indexing (`container[index]`) operation. Read more
1.0.0 · Source§

### impl<I> IndexMut<I> for str
where I: SliceIndex<str>,

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#### fn index_mut(&mut self, index: I) -> &mut I::Output

Performs the mutable indexing (`container[index]`) operation. Read more
1.0.0 · Source§

### impl Ord for str

Implements ordering of strings.

Strings are ordered lexicographically by their byte values. This orders Unicode code points based on their positions in the code charts. This is not necessarily the same as “alphabetical” order, which varies by language and locale. Sorting strings according to culturally-accepted standards requires locale-specific data that is outside the scope of the `str` type.

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#### fn cmp(&self, other: &str) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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### impl<'a> PartialEq<&str> for ByteStr

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#### fn eq(&self, other: &&str) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<'a> PartialEq<ByteStr> for &str

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#### fn eq(&self, other: &ByteStr) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<'a> PartialEq<ByteStr> for str

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#### fn eq(&self, other: &ByteStr) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<'a> PartialEq<str> for ByteStr

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#### fn eq(&self, other: &str) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
1.0.0 · Source§

### impl PartialEq for str

Source§

#### fn eq(&self, other: &str) -> bool

Tests for `self` and `other` values to be equal, and is used by `==`.
1.0.0 · Source§

#### fn ne(&self, other: &Rhs) -> bool

Tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
1.0.0 · Source§

### impl PartialOrd for str

Implements comparison operations on strings.

Strings are compared lexicographically by their byte values. This compares Unicode code points based on their positions in the code charts. This is not necessarily the same as “alphabetical” order, which varies by language and locale. Comparing strings according to culturally-accepted standards requires locale-specific data that is outside the scope of the `str` type.

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#### fn partial_cmp(&self, other: &str) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
1.0.0 · Source§

#### fn lt(&self, other: &Rhs) -> bool

Tests less than (for `self` and `other`) and is used by the `<` operator. Read more
1.0.0 · Source§

#### fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
1.0.0 · Source§

#### fn gt(&self, other: &Rhs) -> bool

Tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
1.0.0 · Source§

#### fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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### impl<'b> Pattern for &'b str

Non-allocating substring search.

Will handle the pattern `""` as returning empty matches at each character boundary.

#### §Examples

    assert_eq!("Hello world".find("world"), Some(6));

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#### fn is_prefix_of(self, haystack: &str) -> bool

🔬This is a nightly-only experimental API. (`pattern` #27721)

Checks whether the pattern matches at the front of the haystack.

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#### fn is_contained_in(self, haystack: &str) -> bool

🔬This is a nightly-only experimental API. (`pattern` #27721)

Checks whether the pattern matches anywhere in the haystack

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#### fn strip_prefix_of(self, haystack: &str) -> Option<&str>

🔬This is a nightly-only experimental API. (`pattern` #27721)

Removes the pattern from the front of haystack, if it matches.

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#### fn is_suffix_of<'a>(self, haystack: &'a str) -> bool
where Self::Searcher<'a>: ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (`pattern` #27721)

Checks whether the pattern matches at the back of the haystack.

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#### fn strip_suffix_of<'a>(self, haystack: &'a str) -> Option<&'a str>
where Self::Searcher<'a>: ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (`pattern` #27721)

Removes the pattern from the back of haystack, if it matches.

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#### type Searcher<'a> = StrSearcher<'a, 'b>

🔬This is a nightly-only experimental API. (`pattern` #27721)
Associated searcher for this pattern
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#### fn into_searcher(self, haystack: &str) -> StrSearcher<'_, 'b>

🔬This is a nightly-only experimental API. (`pattern` #27721)
Constructs the associated searcher from `self` and the `haystack` to search in.
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#### fn as_utf8_pattern(&self) -> Option<Utf8Pattern<'_>>

🔬This is a nightly-only experimental API. (`pattern` #27721)
Returns the pattern as utf-8 bytes if possible.
1.73.0 · Source§

### impl SliceIndex<str> for (Bound<usize>, Bound<usize>)

Implements substring slicing for arbitrary bounds.

Returns a slice of the given string bounded by the byte indices provided by each bound.

This operation is O(1).

#### §Panics

Panics if `begin` or `end` (if it exists and once adjusted for inclusion/exclusion) does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `begin > end`, or if `end > len`.

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#### type Output = str

The output type returned by methods.
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#### fn get(self, slice: &str) -> Option<&str>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
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#### fn get_mut(self, slice: &mut str) -> Option<&mut str>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
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#### unsafe fn get_unchecked(self, slice: *const str) -> *const str

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
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#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut str

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
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#### fn index(self, slice: &str) -> &str

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
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#### fn index_mut(self, slice: &mut str) -> &mut str

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.20.0 · Source§

### impl SliceIndex<str> for Range<usize>

Implements substring slicing with syntax `&self[begin .. end]` or `&mut self[begin .. end]`.

Returns a slice of the given string from the byte range [`begin`, `end`).

This operation is O(1).

Prior to 1.20.0, these indexing operations were still supported by direct implementation of `Index` and `IndexMut`.

#### §Panics

Panics if `begin` or `end` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `begin > end`, or if `end > len`.

#### §Examples

    let s = "Löwe 老虎 Léopard";
    assert_eq!(&s[0 .. 1], "L");

    assert_eq!(&s[1 .. 9], "öwe 老");

    // these will panic:
    // byte 2 lies within `ö`:
    // &s[2 ..3];

    // byte 8 lies within `老`
    // &s[1 .. 8];

    // byte 100 is outside the string
    // &s[3 .. 100];

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#### type Output = str

The output type returned by methods.
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#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
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#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
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#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
Source§

### impl SliceIndex<str> for Range<usize>

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.20.0 · Source§

### impl SliceIndex<str> for RangeFrom<usize>

Implements substring slicing with syntax `&self[begin ..]` or `&mut self[begin ..]`.

Returns a slice of the given string from the byte range [`begin`, `len`). Equivalent to `&self[begin .. len]` or `&mut self[begin .. len]`.

This operation is O(1).

Prior to 1.20.0, these indexing operations were still supported by direct implementation of `Index` and `IndexMut`.

#### §Panics

Panics if `begin` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), or if `begin > len`.

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
Source§

### impl SliceIndex<str> for RangeFrom<usize>

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.20.0 · Source§

### impl SliceIndex<str> for RangeFull

Implements substring slicing with syntax `&self[..]` or `&mut self[..]`.

Returns a slice of the whole string, i.e., returns `&self` or `&mut self`. Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`. Unlike other indexing operations, this can never panic.

This operation is O(1).

Prior to 1.20.0, these indexing operations were still supported by direct implementation of `Index` and `IndexMut`.

Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`.

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.26.0 · Source§

### impl SliceIndex<str> for RangeInclusive<usize>

Implements substring slicing with syntax `&self[begin ..= end]` or `&mut self[begin ..= end]`.

Returns a slice of the given string from the byte range [`begin`, `end`]. Equivalent to `&self [begin .. end + 1]` or `&mut self[begin .. end + 1]`, except if `end` has the maximum value for `usize`.

This operation is O(1).

#### §Panics

Panics if `begin` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), if `end` does not point to the ending byte offset of a character (`end + 1` is either a starting byte offset or equal to `len`), if `begin > end`, or if `end >= len`.

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
Source§

### impl SliceIndex<str> for RangeInclusive<usize>

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.20.0 · Source§

### impl SliceIndex<str> for RangeTo<usize>

Implements substring slicing with syntax `&self[.. end]` or `&mut self[.. end]`.

Returns a slice of the given string from the byte range [0, `end`). Equivalent to `&self[0 .. end]` or `&mut self[0 .. end]`.

This operation is O(1).

Prior to 1.20.0, these indexing operations were still supported by direct implementation of `Index` and `IndexMut`.

#### §Panics

Panics if `end` does not point to the starting byte offset of a character (as defined by `is_char_boundary`), or if `end > len`.

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
1.26.0 · Source§

### impl SliceIndex<str> for RangeToInclusive<usize>

Implements substring slicing with syntax `&self[..= end]` or `&mut self[..= end]`.

Returns a slice of the given string from the byte range [0, `end`]. Equivalent to `&self [0 .. end + 1]`, except if `end` has the maximum value for `usize`.

This operation is O(1).

#### §Panics

Panics if `end` does not point to the ending byte offset of a character (`end + 1` is either a starting byte offset as defined by `is_char_boundary`, or equal to `len`), or if `end >= len`.

Source§

#### type Output = str

The output type returned by methods.
Source§

#### fn get(self, slice: &str) -> Option<&Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, if in bounds.
Source§

#### fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output>

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, if in bounds.
Source§

#### unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable pointer to the output at this location, without performing any bounds checking. Read more
Source§

#### fn index(self, slice: &str) -> &Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a shared reference to the output at this location, panicking if out of bounds.
Source§

#### fn index_mut(self, slice: &mut str) -> &mut Self::Output

🔬This is a nightly-only experimental API. (`slice_index_methods`)
Returns a mutable reference to the output at this location, panicking if out of bounds.
Source§

### impl<'a> TryFrom<&'a ByteStr> for &'a str

Source§

#### type Error = Utf8Error

The type returned in the event of a conversion error.
Source§

#### fn try_from(s: &'a ByteStr) -> Result<Self, Self::Error>

Performs the conversion.
Source§

### impl<'a> TryFrom<&'a mut ByteStr> for &'a mut str

Source§

#### type Error = Utf8Error

The type returned in the event of a conversion error.
Source§

#### fn try_from(s: &'a mut ByteStr) -> Result<Self, Self::Error>

Performs the conversion.
1.0.0 · Source§

### impl Eq for str

1.65.0 · Source§

### impl !Error for &str

Source§

### impl StructuralPartialEq for str

Source§

### impl UnsizedConstParamTy for str

## Auto Trait Implementations§

§

### impl Freeze for str

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### impl RefUnwindSafe for str

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### impl Send for str

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### impl !Sized for str

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### impl Sync for str

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### impl Unpin for str

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### impl UnwindSafe for str

## Blanket Implementations§

Source§

### impl<T> Any for T
where T: 'static + ?Sized,

Source§

#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
Source§

### impl<T> Borrow<T> for T
where T: ?Sized,

Source§

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
Source§

### impl<T> BorrowMut<T> for T
where T: ?Sized,

Source§

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more