比较php中的各种排序函数

通过简单的代码，比较php中sort，natsort和usort的不同。

My First Hello World in PHP
";        echo "
Sorting the dates using sort() function:
";    sort($dateList);        foreach ($dateList as $date)    {        echo "
$date
";    }        echo "
";        echo "
Sorting the dates using natsort() function:
";    natsort($dateList);        foreach ($dateList as $date)    {        echo "
$date
";    }        echo "
";        function opDateSort($a, $b)    {        if ($a == $b) return 0;                list($aMonth, $aDay, $aYear) = explode("-", $a);        list($bMonth, $bDay, $bYear) = explode("-", $b);                $aMonth = str_pad($aMonth, 2, "0", STR_PAD_LEFT);        $bMonth = str_pad($bMonth, 2, "0", STR_PAD_LEFT);        $aDay = str_pad($aDay, 2, "0", STR_PAD_LEFT);        $bDay = str_pad($bDay, 2, "0", STR_PAD_LEFT);                $aDate = $aYear.$aMonth.$aDay;        $bDate = $bYear.$bMonth.$bDay;                return $aDate>$bDate?1:-1;    }        echo "
Sorting the dates using usort() with user defined comparing function:
";    usort($dateList, 'opDateSort');        foreach ($dateList as $date)    {        echo "
$date
";    }        echo "
";        echo "";?>

其中info.txt的内容为

4-1-196910-25-19879-11-19826-18-19284-27-19276-12-19237-16-19227-23-1921

结果如图所示