strcoll

(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)

strcoll — 基于区域设置的字符串比较

说明

strcoll ( string $str1 , string $str2 ) : int

注意该比较区分大小写。和 strcmp() 不同，该函数不是二进制安全的。

strcoll() 使用当前区域设置进行比较。如果当前区域为 C 或 POSIX，该函数等同于 strcmp()。

参数

str1: 第一个字符串。
str2: 第二个字符串。

返回值

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。

更新日志

版本	说明
4.2.3	函数在 Win32 平台可用。

参见

preg_match() - 执行匹配正则表达式
strcmp() - 二进制安全字符串比较
strcasecmp() - 二进制安全比较字符串（不区分大小写）
substr() - 返回字符串的子串
stristr() - strstr 函数的忽略大小写版本
strncasecmp() - 二进制安全比较字符串开头的若干个字符（不区分大小写）
strncmp() - 二进制安全比较字符串开头的若干个字符
strstr() - 查找字符串的首次出现
setlocale() - 设置地区信息

User Contributed Notes

mkroese at eljakim dot nl 02-Aug-2019 09:13


You should not rely on this function to properly compare localized strings.



<?php

$a = "?sterreich";

$b = "Oesterreich";

$z = "Zeta";



echo setlocale(LC_ALL, 0) . PHP_EOL; // (on my mac: C/en_US.UTF-8/C/C/C/C)

echo strcoll($a, $b) . PHP_EOL; // 116

echo strcoll($b, $a) . PHP_EOL; // -116

echo strcoll($a, $z) . PHP_EOL; // 105



echo setlocale(LC_ALL, "de_DE") . PHP_EOL; // de_DE

echo strcoll($a, $b) . PHP_EOL; // 135

echo strcoll($b, $a) . PHP_EOL; // -135

echo strcoll($a, $z) . PHP_EOL; // 124



$collator = new Collator("de_DE");

echo $collator->compare($a, $b); // 1

echo $collator->compare($b, $a); // -1

echo $collator->compare($a, $z); // -1

?>



Using the Collator (from the intl module) you will get the expected result for e.g. sorting such that the string "?sterreich" will rank higher than "Zeta", but after "Oesterreich".



strcoll's output will differ per platform, locale and used c library, while the Collator will give more stable results on different platforms.

sakkarinlaohawisut15 at hotmail dot com 22-Mar-2003 11:31


strcoll()'s behavior is sometimes a little bit confusing. It depends on LC_COLLATE in your locale.



<?php



 $a = 'a';

 $b = 'A';



 print strcmp ($a, $b) . "\n"; // prints 1



setlocale (LC_COLLATE, 'C');

 print "C: " . strcoll ($a, $b) . "\n"; // prints 1



 setlocale (LC_COLLATE, 'de_DE');

 print "de_DE: " . strcoll ($a, $b) . "\n"; // prints -2



 setlocale (LC_COLLATE, 'de_CH');

print "de_CH: " . strcoll ($a, $b) . "\n"; // prints -2



 setlocale (LC_COLLATE, 'en_US');

 print "en_US: " . strcoll ($a, $b) . "\n"; // prints -2



?>



This is useful e. g. if want to sort an array by using strcoll:



<?php



 $a = array ('a', 'A', '?', '?', 'b', 'B');



 setlocale (LC_COLLATE, 'C');

 usort ($a, 'strcoll');

 print_r ($a);



?>



This is like sort($a):

 Array

 (

    [0] => A

    [1] => B

  [2] => a

    [3] => b

    [4] => ?

    [5] => ?

 )



<?php



 setlocale (LC_COLLATE, 'de_DE');

usort ($a, 'strcoll');

 print_r ($a)



?>

 

This is completely different:

 Array

 (

    [0] => a

    [1] => A

    [2] => ?

    [3] => ?

    [4] => b

  [5] => B

 )

27-Aug-2002 07:05


Note that some platforms implement strcmp() and strcasecmp() according to the current locale when strings are not binary equal, so that strcmp() and strcoll() will return the same value! This depends on how the PHP strcmp() function is compiled (i.e. if it uses the platform specific strcmp() found in its standard library!).

In that case, the only difference between strcoll() and strcmp() is that strcoll() may return 0 for distinct strings(i.e. consider strings are equal) while strcmp() will differentiate them if they have distinct binary encoding! This typically occurs on Asian systems.

What you can be sure is that strcmp() will always differentiate strings that are encoded differently, but the relative order may still use the current locale setting for collation order!