Compares two "PHP-standardized" version number strings

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# version_compare

(PHP 4 >= 4.1.0, PHP 5)

version_compare — Compares two "PHP-standardized" version number strings

### Description

mixed version_compare ( string `$version1` , string `$version2` [, string `$operator` ] )

version_compare() compares two "PHP-standardized" version number strings. This is useful if you would like to write programs working only on some versions of PHP.

The function first replaces _, - and + with a dot . in the version strings and also inserts dots . before and after any non number so that for example '4.3.2RC1' becomes '4.3.2.RC.1'. Then it splits the results like if you were using explode('.', $ver). Then it compares the parts starting from left to right. If a part contains special version strings these are handled in the following order: any string not found in this list < dev < alpha = a < beta = b < RC = rc < # < pl = p. This way not only versions with different levels like '4.1' and '4.1.2' can be compared but also any PHP specific version containing development state.

### Parameters

`version1`

  First version number.

`version2`

  Second version number.

`operator`

  If you specify the third optional `operator` argument, you can test for a particular relationship. The possible operators are: <, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne respectively.

  This parameter is case-sensitive, so values should be lowercase.

### Return Values

By default, version_compare() returns -1 if the first version is lower than the second, 0 if they are equal, and 1 if the second is lower.

When using the optional `operator` argument, the function will return `TRUE` if the relationship is the one specified by the operator, `FALSE` otherwise.

### Examples

The examples below use the `PHP_VERSION` constant, because it contains the value of the PHP version that is executing the code.

Example #1 version_compare() examples

`<?php
if (version_compare(PHP_VERSION, '6.0.0') >= 0) {
echo 'I am at least PHP version 6.0.0, my version: ' . PHP_VERSION . "\n";
}
if (version_compare(PHP_VERSION, '5.3.0') >= 0) {
echo 'I am at least PHP version 5.3.0, my version: ' . PHP_VERSION . "\n";
}
if (version_compare(PHP_VERSION, '5.0.0', '>=')) {
echo 'I am using PHP 5, my version: ' . PHP_VERSION . "\n";
}
if (version_compare(PHP_VERSION, '5.0.0', '<')) {
echo 'I am using PHP 4, my version: ' . PHP_VERSION . "\n";
}
?>`

### Notes

> Note:

> The `PHP_VERSION` constant holds current PHP version.

> Note:

> Note that pre-release versions, such as 5.3.0-dev, are considered lower than their final release counterparts (like 5.3.0).

> Note:

> Special version strings such as alpha and beta are case sensitive. Version strings from arbitrary sources that do not adhere to the PHP standard may need to be lowercased via strtolower() before calling version_compare().

### See Also

- phpversion() - Gets the current PHP version
- php_uname() - Returns information about the operating system PHP is running on
- function_exists() - Return TRUE if the given function has been defined

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