PHP 5.5.15 is released

strcoll

(PHP 4 >= 4.0.5, PHP 5)

strcollLocale based string comparison

Description

int strcoll ( string $str1 , string $str2 )

Note that this comparison is case sensitive, and unlike strcmp() this function is not binary safe.

strcoll() uses the current locale for doing the comparisons. If the current locale is C or POSIX, this function is equivalent to strcmp().

Parameters

str1

The first string.

str2

The second string.

Return Values

Returns < 0 if str1 is less than str2; > 0 if str1 is greater than str2, and 0 if they are equal.

Changelog

Version Description
4.2.3 This function now works on win32.

See Also

  • preg_match() - Perform a regular expression match
  • strcmp() - Binary safe string comparison
  • strcasecmp() - Binary safe case-insensitive string comparison
  • substr() - Return part of a string
  • stristr() - Case-insensitive strstr
  • strncasecmp() - Binary safe case-insensitive string comparison of the first n characters
  • strncmp() - Binary safe string comparison of the first n characters
  • strstr() - Find first occurrence of a string
  • setlocale() - Set locale information

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User Contributed Notes 2 notes

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1
Anonymous
11 years ago
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!
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0
sakkarinlaohawisut15 at hotmail dot com
11 years ago
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
)
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