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version_compare

(PHP 4 >= 4.1.0, PHP 5)

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

说明

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.

参数

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.

返回值

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.

范例

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";
}
?>

注释

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).

参见

PHP 选项/信息 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Compares two "PHP-standardized" version number strings

用户评论:

rogier (30-Nov-2011 04:43)

Please note that supplying an operator that is not listed (e.g. ===), this function returns NULL instead of false.

Tested on PHP5.3.0, Win32

Steve Kamerman (24-Jun-2011 08:07)

I know I'm splitting hairs here, but if you're OCD like me

(version_compare(PHP_VERSION, '5.3.0') >= 0)

is about 13% faster than

(version_compare(PHP_VERSION, '5.3.0', '>=')

<?php
$count = 200000;
$start = microtime(true);
for($i=0;$i<$count;$i++) (version_compare(PHP_VERSION, '5.3.0') >= 0);
echo "Real Operator: ".(microtime(true) - $start)."\n";
$start = microtime(true);
for($i=0;$i<$count;$i++) (version_compare(PHP_VERSION, '5.3.0', '>='));
echo "String Operator: ".(microtime(true) - $start)."\n";
?>

loaded67 at hotmail dot com (30-Sep-2009 12:53)

This function is also usefull when working with multiple installations.

As php5.3+ will not have E_STRICT in the error_reporting anymore you can state:

<?php
ini_set('error_reporting', (version_compare(PHP_VERSION, '5.3.0', '<') ? E_ALL|E_STRICT : E_ALL));
?>

Giving you all the error error reporting you want...

Sina Salek (15-Aug-2009 10:47)

Sometimes the code is forward compatible, for example when the code is compatible with all future PHP5 releases.
This function supports .x, for the above example it's : 5.x
<?php
    function versionCompare($version1,$version2,$operand) {
        $v1Parts=explode('.',$version1);
        $version1.=str_repeat('.0',3-count($v1Parts));
        $v2Parts=explode('.',$version2);
        $version2.=str_repeat('.0',3-count($v2Parts));
        $version1=str_replace('.x','.1000',$version1);
        $version2=str_replace('.x','.1000',$version2);       
        return version_compare($version1,$version2,$operand);
    }
?>

---
Sina Salek
http://sina.salek.ws/en/contact

insid0r at yahoo dot com (06-Mar-2009 09:05)

Since this function considers 1 < 1.0 < 1.0.0, others might find this function useful (which considers 1 == 1.0):

<?php
//Compare two sets of versions, where major/minor/etc. releases are separated by dots.
//Returns 0 if both are equal, 1 if A > B, and -1 if B < A.
function version_compare2($a, $b)
{
    $a = explode(".", rtrim($a, ".0")); //Split version into pieces and remove trailing .0
    $b = explode(".", rtrim($b, ".0")); //Split version into pieces and remove trailing .0
    foreach ($a as $depth => $aVal)
    { //Iterate over each piece of A
        if (isset($b[$depth]))
        { //If B matches A to this depth, compare the values
            if ($aVal > $b[$depth]) return 1; //Return A > B
            else if ($aVal < $b[$depth]) return -1; //Return B > A
            //An equal result is inconclusive at this point
        }
        else
        { //If B does not match A to this depth, then A comes after B in sort order
            return 1; //so return A > B
        }
    }
    //At this point, we know that to the depth that A and B extend to, they are equivalent.
    //Either the loop ended because A is shorter than B, or both are equal.
    return (count($a) < count($b)) ? -1 : 0;
}
?>

Niraj Bhawnani (10-Feb-2009 02:10)

This function also works nicely when comparing IP addresses :)

bishop (07-Mar-2008 06:54)

<?php
// quick & dirty way to barricade your code during version transitions
assert('version_compare("5", PHP_VERSION, "<"); // requires PHP 5 or higher');
?>

Rickard Andersson (30-Oct-2007 09:18)

It should be noted that version_compare() considers 1 < 1.0 < 1.0.0 etc. I'm guessing this is due to the left-to-right nature of the algorithm.

Jonathon dot Reinhart at gmail dot com (30-Oct-2007 03:38)

I know this is somewhat incomplete, but it did a fair enough job for what I needed.  I was writing some code that needed done immediately on a server that was to be upgraded some time in the future.  Here is a quick replacement for version_compare (without the use of the operator argument). Feel free to add to this / complete it.

<?php
function version_compare2($version1, $version2)
{
    $v1 = explode('.',$version1);
    $v2 = explode('.',$version2);
   
    if ($v1[0] > $v2[0])
        $ret = 1;
    else if ($v1[0] < $v2[0])
        $ret = -1;
   
    else    // Major ver are =
    {
        if ($v1[1] > $v2[1])
            $ret = 1;
        else if ($v1[1] < $v2[1])
            $ret = -1;
       
        else  // Minor ver are =
        {
            if ($v1[2] > $v2[2])
                $ret = 1;
            else if ($v1[2] < $v2[2])
                $ret = -1;
            else
                $ret = 0;
        }
    }
   
    return $ret;
}
?>

opendb at iamvegan dot net (11-Jun-2007 01:01)

Something that may trip some folks up, but is useful to mention is that the following version comparison does not work quite as I expected:
    version_compare('1.0.1', '1.0pl1', '>')

However, its quite easy to get working:
    version_compare('1.0.1', '1.0.0pl1', '>')

arnoud at procurios dot nl (29-Sep-2004 10:28)

If you're careful, this function actualy works quite nicely for comparing version numbers from programs other than PHP itself. I've used it to compare MySQL version numbers. The only issue is that version_compare doesn't recognize the 'gamma' addition that mysql uses as being later than 'alpha' or 'beta', because the latter two are treated specially. If you keep this in mind though, you should have no problems.

mina86 at tlen dot pl (01-Jul-2004 03:40)

Here's a wrapper which is more tolerant as far as order of arguments is considered:

<?php
function ver_cmp($arg1, $arg2 = null, $arg3 = null) {
  static $phpversion = null;
  if ($phpversion===null) $phpversion = phpversion();

  switch (func_num_args()) {
  case 1: return version_compare($phpversion, $arg1);
  case 2:
    if (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg1))
      return version_compare($phpversion, $arg2, $arg1);
    elseif (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg2))
      return version_compare($phpversion, $arg1, $arg2);
    return version_compare($arg1, $arg2);
  default:
    $ver1 = $arg1;
    if (preg_match('/^[lg][te]|[<>]=?|[!=]?=|eq|ne|<>$/i', $arg2))
      return version_compare($arg1, $arg3, $arg2);
    return version_compare($arg1, $arg2, $arg3);
  }
}
?>

It also uses phpversion() as a default version if only one string is present. It can make your code look nicer 'cuz you can now write:
<?php if (ver_cmp($version1, '>=', $version2)) something; ?>
and to check a version string against the PHP's version you might use:
<?php if (ver_cmp('>=', $version)) something; ?>
instead of using phpversion().

eric at themepark dot com (22-Jun-2004 05:50)

[editors note]
snipbit fixed after comment from Matt Mullenweg

--jm
[/editors note]

so in a nutshell... I believe it works best like this:

<?php
if (version_compare(phpversion(), "4.3.0", ">=")) {
  // you're on 4.3.0 or later
} else {
  // you're not
}
?>

sam at wyvern dot non-spammers-remove dot com dot au (23-May-2004 07:18)

Actually, it works to any degree:

<?php
version_compare('1.2.3.4RC7.7', '1.2.3.4RC7.8')
version_compare('8.2.50.4', '8.2.52.6')
?>

will both give -1 (ie the left is lower than the right).