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# version_compare

(PHP 4 >= 4.1.0, PHP 5)

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

## Description

int 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.

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.

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.

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 1 if the relationship is the one specified by the operator, 0 otherwise.

Beispiel 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"); ?>`

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