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(PHP 4, PHP 5)
strnatcmp — 使用自然排序算法比较字符串
$str1
, string $str2
)该函数实现了以人类习惯对数字型字符串进行排序的比较算法,这就是“自然顺序”。注意该比较区分大小写。
str1
第一个字符串。
str2
第二个字符串。
与其他字符串比较函数类似,如果 str1
小于
str2
返回 < 0;
如果 str1
大于 str2
返回 > 0;如果两者相等,返回 0。
下面的例子展示了该算法与计算机常规字符串比较算法( strcmp() 所使用的)的区别:
<?php
$arr1 = $arr2 = array( "img12.png" , "img10.png" , "img2.png" , "img1.png" );
echo "Standard string comparison\n" ;
usort ( $arr1 , "strcmp" );
print_r ( $arr1 );
echo "\nNatural order string comparison\n" ;
usort ( $arr2 , "strnatcmp" );
print_r ( $arr2 );
?>
以上例程会输出:
Standard string comparison Array ( [0] => img1.png [1] => img10.png [2] => img12.png [3] => img2.png )Natural order string comparison Array ( [0] => img1.png [1] => img2.png [2] => img10.png [3] => img12.png )
[#1] Zero [2010-12-04 14:14:28]
If you want to compare $_SESSION variables to a string use this
<?php
if(isset($_SESSION['usertype']))
{
echo "usertype " .$_SESSION['usertype'];
$ut = $_SESSION['usertype'];
if(strnatcmp($ut,"admin"))
{
echo "hello admin";
}
}
?>
[#2] thomas at uninet dot se [2006-07-25 00:50:13]
There seems to be a bug in the localization for strnatcmp and strnatcasecmp. I searched the reported bugs and found a few entries which were up to four years old (but the problem still exists when using swedish characters).
These functions might work instead.
<?php
function _strnatcasecmp($left, $right) {
return _strnatcmp(strtolower($left), strtolower($right));
}
function _strnatcmp($left, $right) {
while((strlen($left) > 0) && (strlen($right) > 0)) {
if(preg_match('/^([^0-9]*)([0-9].*)$/Us', $left, $lMatch)) {
$lTest = $lMatch[1];
$left = $lMatch[2];
} else {
$lTest = $left;
$left = '';
}
if(preg_match('/^([^0-9]*)([0-9].*)$/Us', $right, $rMatch)) {
$rTest = $rMatch[1];
$right = $rMatch[2];
} else {
$rTest = $right;
$right = '';
}
$test = strcmp($lTest, $rTest);
if($test != 0) {
return $test;
}
if(preg_match('/^([0-9]+)([^0-9].*)?$/Us', $left, $lMatch)) {
$lTest = intval($lMatch[1]);
$left = $lMatch[2];
} else {
$lTest = 0;
}
if(preg_match('/^([0-9]+)([^0-9].*)?$/Us', $right, $rMatch)) {
$rTest = intval($rMatch[1]);
$right = $rMatch[2];
} else {
$rTest = 0;
}
$test = $lTest - $rTest;
if($test != 0) {
return $test;
}
}
return strcmp($left, $right);
}
?>
The code is not optimized. It was just made to solve my problem.