# version_compare

(PHP 4 >= 4.0.7, 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: dev < alpha = a < beta = b < RC < pl. 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. Using this argument, the function will return `TRUE` if the relationship is the one specified by the operator, `FALSE` otherwise.

### Return Values

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.

### Examples

Example#1 version_compare() example

`<?php
// prints -1
echo version_compare("4.0.4", "4.0.6");
// these all print 1
echo version_compare("4.0.4", "4.0.6", "<");
echo version_compare("4.0.6", "4.0.6", "eq");
?>`

### Notes

> Note: The `PHP_VERSION` constant holds current PHP version.