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    strcasecmp

    (PHP 4, PHP 5, PHP 7, PHP 8)

    strcasecmp — Comparación de string segura a nivel binario e insensible a mayúsculas y minúsculas

    Descripción

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

    Comparación de string segura a nivel binario e insensible a mayúsculas y minúsculas.

    Parámetros

    str1

    El primer string

    str2

    El segundo string

    Valores devueltos

    Devuelve < 0 si str1 es menor que str2; > 0 si str1 es mayor que str2 y 0 si son iguales.

    Ejemplos

    Ejemplo #1 Ejemplo de strcasecmp()

    <?php
    $var1     = "Hello";
    $var2 = "hello";
    if (    strcasecmp($var1, $var2) == 0) {
    echo     '$var1 is equal to $var2 in a case-insensitive string comparison';
    }
    ?>

    Ver también

    • strcmp() - Comparación de string segura a nivel binario
    • preg_match() - Realiza una comparación con una expresión regular
    • substr_compare() - Comparación segura a nivel binario de dos o más strings desde un índice hasta una longitud de caracteres dada
    • strncasecmp() - Comparación de los primeros n caracteres de cadenas, segura con material binario e insensible a mayúsculas y minúsculas
    • stristr() - strstr insensible a mayúsculas y minúsculas
    • substr() - Devuelve parte de una cadena

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    User Contributed Notes 4 notes

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    20
    chris at cmbuckley dot co dot uk
    12 years ago
    A simple multibyte-safe case-insensitive string comparison:

    <?php

    function mb_strcasecmp($str1, $str2, $encoding = null) {
        if (    null === $encoding) { $encoding = mb_internal_encoding(); }
        return     strcmp(mb_strtoupper($str1, $encoding), mb_strtoupper($str2, $encoding));
    }

    ?>

    Caveat: watch out for edge cases like "ß".
    up
    11
    Anonymous
    22 years ago
    The sample above is only true on some platforms that only use a simple 'C' locale, where individual bytes are considered as complete characters that are converted to lowercase before being differentiated.

    Other locales (see LC_COLLATE and LC_ALL) use the difference of collation order of characters, where characters may be groups of bytes taken from the input strings, or simply return -1, 0, or 1 as the collation order is not simply defined by comparing individual characters but by more complex rules.

    Don't base your code on a specific non null value returned by strcmp() or strcasecmp(): it is not portable. Just consider the sign of the result and be sure to use the correct locale!
    up
    6
    alvaro at demogracia dot com
    14 years ago
    Don't forget this is a single-byte function: in Unicode strings it'll provide incoherent results as soon as both strings differ only in case. There doesn't seem to exist a built-in multi-byte alternative so you need to write your own, taking into account both character encoding and collation.
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    0
    chrislarham at NOSPAM dot outlook dot com
    6 years ago
    I didn't see any explanation in the documentation as to precisely how the positive/negative return values are calculated for unequal strings.

    After a bit of experimentation it appears that it's the difference in alphabetical position of the first character in unequal strings.

    For example, the letter 'z' is the 26th letter while the letter 'a' is the 1st letter:

    <?php

          $zappl     = "zappl";
              $apple = "apple";

          echo     strcasecmp($zappl, $apple); #outputs 25 [26 - 1]
              echo strcasecmp($apple, $zappl); #outputs -25 [1 - 26]

    ?>

    This might be incredibly obvious to most people, but hopefully it will clarify the calculation process for some others.
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