strcoll

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

strcoll — Confronto tra stringhe basato sulle impostazioni locali

Descrizione

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

Restituisce < 0 se str1 è minore di str2; > 0 se str1 è maggiore di str2, e 0 se sono uguali. strcoll() utilizza le impostazioni locali per il confronto. Se le impostazioni locali sono conformi al C o a POSIX, allora la funzione è equivalente a strcmp().

Attenzione. questo confronto distingue tra maiuscole e minuscole, e, diversamente da strcmp() non è affidabile con i dati binari.

Nota:
strcoll() è stato aggiunto in PHP 4.0.5, ma sui sistemi win32 non è stato abilitato fino alla versione 4.2.3.

Vedere anche ereg(), strcmp(), strcasecmp(), substr(), stristr(), strncasecmp(), strncmp(), strstr() e setlocale().

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User Contributed Notes 3 notes

down

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!

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mkroese at eljakim dot nl ¶

5 years ago

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.

down

-1

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
 )

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