strcoll

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

    strcoll — Locale based string comparison

    Description

    strcoll(string $string1, string $string2): int

    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

    string1

    The first string.

    string2

    The second string.

    Return Values

    Returns < 0 if string1 is less than string2; > 0 if string1 is greater than string2, and 0 if they are equal.

    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 the first occurrence of a string
    • setlocale() - Set locale information

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    User Contributed Notes 3 notes

    up
    8
    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!
    up
    6
    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.
    up
    -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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