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比较php中的各种排序函数

2015-02-11 08:10 183 查看
通过简单的代码,比较php中sort,natsort和usort的不同。
<html>
<head>
<style type="text/css">
li{
border:2px  solid  black;
padding: 0.5em;
width: auto;
margin: 0.5em;
}
p{
font-size: 20px;
color: blue;
}
ol li{
border: 1px solid red;
margin: 0px;
}
</style>
</head>
<body>
<h3>My First Hello World in PHP</h3>
<?php
$dateFile = fopen("info.txt", "r");

while ($dateLine = fgets($dateFile, 4096))
{
$dateList[] = $dateLine;
}

echo "<ul>";

echo "<li><p>Sorting the dates using sort() function:</p><ol>";
sort($dateList);

foreach ($dateList as $date)
{
echo "<li>$date</li>";
}

echo "</ol></li>";

echo "<li><p>Sorting the dates using natsort() function:</p><ol>";
natsort($dateList);

foreach ($dateList as $date)
{
echo "<li>$date</li>";
}

echo "</ol></li>";

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 "<li><p>Sorting the dates using usort() with user defined comparing function:</p><ol>";
usort($dateList, 'opDateSort');

foreach ($dateList as $date)
{
echo "<li>$date</li>";
}

echo "</ol></li>";

echo "</ul>";
?>
</body>
</html>
其中info.txt的内容为
4-1-1969
10-25-1987
9-11-1982
6-18-1928
4-27-1927
6-12-1923
7-16-1922
7-23-1921
结果如图所示



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