Return information about characters used in a string

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String Functions
PHP Manual

# count_chars

(PHP 4, PHP 5)

count_chars — Return information about characters used in a string

### Description

mixed count_chars ( string `$string` [, int `$mode` = 0 ] )

Counts the number of occurrences of every byte-value (0..255) in `string` and returns it in various ways.

### Parameters

`string`

  The examined string.

`mode`

  See return values.

### Return Values

Depending on `mode` count_chars() returns one of the following:

- 0 - an array with the byte-value as key and the frequency of every byte as value.
- 1 - same as 0 but only byte-values with a frequency greater than zero are listed.
- 2 - same as 0 but only byte-values with a frequency equal to zero are listed.
- 3 - a string containing all unique characters is returned.
- 4 - a string containing all not used characters is returned.

### Examples

Example #1 count_chars() example

`<?php
$data = "Two Ts and one F.";
foreach (count_chars($data, 1) as $i => $val) {
echo "There were $val instance(s) of \"" , chr($i) , "\" in the string.\n";
}
?>`

The above example will output:

    There were 4 instance(s) of " " in the string.
    There were 1 instance(s) of "." in the string.
    There were 1 instance(s) of "F" in the string.
    There were 2 instance(s) of "T" in the string.
    There were 1 instance(s) of "a" in the string.
    There were 1 instance(s) of "d" in the string.
    There were 1 instance(s) of "e" in the string.
    There were 2 instance(s) of "n" in the string.
    There were 2 instance(s) of "o" in the string.
    There were 1 instance(s) of "s" in the string.
    There were 1 instance(s) of "w" in the string.

### See Also

- strpos() - Find position of first occurrence of a string
- substr_count() - Count the number of substring occurrences

convert_uuencode
crc32
String Functions
PHP Manual