strcoll

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!

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, $b) . PHP_EOL; // 116echo strcoll($b, $a) . PHP_EOL; // -116echo strcoll($a, $z) . PHP_EOL; // 105echo setlocale(LC_ALL, "de_DE") . PHP_EOL; // de_DEecho strcoll($a, $b) . PHP_EOL; // 135echo strcoll($b, $a) . PHP_EOL; // -135echo strcoll($a, $z) . PHP_EOL; // 124$collator = new Collator("de_DE");echo $collator->compare($a, $b); // 1echo $collator->compare($b, $a); // -1echo $collator->compare($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()'s behavior is sometimes a little bit confusing. It depends on LC_COLLATE in your locale.<?php $a = 'a'; $b = 'A'; print strcmp ($a, $b) . "\n"; // prints 1setlocale (LC_COLLATE, 'C'); print "C: " . strcoll ($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 )