PHP：version_compare() 在比较 5.2 和 5.2.0 时返回 -1？

Question

version_compare('5.2', '5.2.0'); // returns -1, as if the second parameter is greater!

Isn't 5.2 and 5.2.0 suppose to be equal? (isn't 5.2 and 5.2.0.0 are also equal)?

Answer 1

The documentation says it compares 'two "PHP-standardized" version number strings'.

You're comparing one PHP-standardized version number string with one non-PHP-standardized version number string.

Answer 2

Here's a tweaked compare function which behaves as expected by trimming zero version suffix components, ie 5.2.0 -> 5.2 .

var_dump(my_version_compare('5.1', '5.1.0'));           //  0 - equal
var_dump(my_version_compare('5.1', '5.1.0.0'));         //  0 - equal
var_dump(my_version_compare('5.1.0', '5.1.0.0-alpha')); //  1 - 5.1.0.0-alpha is lower
var_dump(my_version_compare('5.1.0-beta', '5.1.0.0'));  // -1 - 5.1.0-beta is lower

function my_version_compare($ver1, $ver2, $operator = null)
{
    $p = '#(\.0+)+($|-)#';
    $ver1 = preg_replace($p, '', $ver1);
    $ver2 = preg_replace($p, '', $ver2);
    return isset($operator) ? 
        version_compare($ver1, $ver2, $operator) : 
        version_compare($ver1, $ver2);
}

Answer 3

5.2 and 5.2.0 are both PHP-standardized version number strings. AFAIU 5.2 represents 5.2.0, 5.2.1, etc. And result is logical, 5.2 could not be equal to 5.2.1 or 5.2.0 and either it could not be greater than 5.2.0 for example.
So only expected behavior is 5.2 < 5.2.0, 5.2 < 5.2.1, ...

Btw even the documentation states:

This way not only versions with different levels like '4.1' and '4.1.2' can be compared but also ...

Answer 4

Quick PHP function to figure out whether a version is greater than other:

$v1 = "1.101.9999";
$v2 = "1.2";

if ( semver($v1, $v2) ) {
    echo "v1 is greater than v2";
}

function semver($v1, $v2, $version_separator = ".") {

    // DTSC
    $v1_sub = explode($version_separator, $v1);
    $v2_sub = explode($version_separator, $v2);

    for ($i=0; $i < sizeof($v1_sub); $i++) {

        if ( !isset($v2_sub[$i]) ) {
            $v2_sub[$i] = 0;
        }
    
        if ( intval($v1_sub[$i]) > intval($v2_sub[$i]) ) {
            return true;
        } else if ( intval($v1_sub[$i]) < intval($v2_sub[$i]) ) {
            return false;
        }
    
    }

    return false; // Versions are equal - Change this value if you need a specific return for equal versions
}