You should not rely on this function to properly compare localized strings.
<?php
$a = "Österreich";
$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 "Österreich" 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.
strcoll
(PHP 4 >= 4.0.5, PHP 5, PHP 7, PHP 8)
strcoll — Locale based string comparison
Descrição
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().
Parâmetros
-
string1 -
The first string.
-
string2 -
The second string.
Valor Retornado
Returns < 0 if string1 is less than
string2; > 0 if
string1 is greater than
string2, and 0 if they are equal.
Veja Também
- preg_match() - Perform a regular expression match
- strcmp() - Binary safe string comparison
- strcasecmp() - Binary safe case-insensitive string comparison
- substr() - Retorna parte de uma string
- stristr() - Case-insensitive strstr
- strncasecmp() - Comparação binária de strings, insensível a maiúsculas/minúsculas, dos primeiros n caracteres
- strncmp() - Binary safe string comparison of the first n characters
- strstr() - Find the first occurrence of a string
- setlocale() - Set locale information
add a note
User Contributed Notes 3 notes
mkroese at eljakim dot nl ¶
5 years ago
Anonymous ¶
22 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!
sakkarinlaohawisut15 at hotmail dot com ¶
21 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
)
