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strcasecmp

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

strcasecmpComparación insensible a mayúsculas/minúsculas de strings binarios

Descripción

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

Comparación insensible a mayúsculas/minúsculas de strings binarios. La comparación no tiene en cuenta la configuración regional; solo las letras ASCII se comparan de manera insensible a mayúsculas/minúsculas.

Parámetros

string1

El primer string.

string2

El segundo string.

Valores devueltos

Returns a value less than 0 if string1 is less than string2; a value greater than 0 if string1 is greater than string2, and 0 if they are equal. No particular meaning can be reliably inferred from the value aside from its sign.

Historial de cambios

Versión Descripción
8.2.0 This function is no longer guaranteed to return strlen($string1) - strlen($string2) when string lengths are not equal, but may now return -1 or 1 instead.

Ejemplos

Ejemplo #1 Ejemplo con strcasecmp()

<?php
$var1
= "Hello";
$var2 = "hello";
if (
strcasecmp($var1, $var2) == 0) {
echo
'$var1 es igual a $var2 (comparación insensible a mayúsculas/minúsculas)';
}
?>

Ver también

  • strcmp() - Comparación binaria de strings
  • preg_match() - Realiza una búsqueda de coincidencia con una expresión regular estándar
  • substr_compare() - Comparar dos strings desde un offset hasta una longitud en caracteres
  • strncasecmp() - Comparación binaria de strings insensible a mayúsculas/minúsculas
  • stristr() - Versión insensible a mayúsculas y minúsculas de strstr
  • substr() - Devuelve un segmento de string

add a note

User Contributed Notes 4 notes

up
29
chris at cmbuckley dot co dot uk
13 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
23
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.
up
10
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
5
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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