mb_convert_case

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

mb_convert_case — Perform case folding on a string

Description

mb_convert_case(string $string, int $mode, ?string $encoding = null): string

Performs case folding on a string, converted in the way specified by mode.

Parameters

string

The string being converted.

mode

The mode of the conversion. It can be one of MB_CASE_UPPER, MB_CASE_LOWER, MB_CASE_TITLE, MB_CASE_FOLD, MB_CASE_UPPER_SIMPLE, MB_CASE_LOWER_SIMPLE, MB_CASE_TITLE_SIMPLE, MB_CASE_FOLD_SIMPLE.

encoding

The encoding parameter is the character encoding. If it is omitted or null, the internal character encoding value will be used.

Return Values

A case folded version of string converted in the way specified by mode.

Changelog

VersionDescription
8.3.0Implemented conditional casing rules for the Greek letter sigma which only apply to MB_CASE_LOWER and MB_CASE_TITLE modes, not to MB_CASE_LOWER_SIMPLE and MB_CASE_TITLE_SIMPLE.
7.3.0Added support for MB_CASE_FOLD, MB_CASE_UPPER_SIMPLE, MB_CASE_LOWER_SIMPLE, MB_CASE_TITLE_SIMPLE, and MB_CASE_FOLD_SIMPLE as mode.

Examples

Example #1 mb_convert_case() example

<?php
$str = "mary had a Little lamb and she loved it so";
$str = mb_convert_case($str, MB_CASE_UPPER, "UTF-8");
echo $str, PHP_EOL;
$str = mb_convert_case($str, MB_CASE_TITLE, "UTF-8");
echo $str, PHP_EOL;
?>

Example #2 mb_convert_case() example with non-Latin UTF-8 text

<?php
$str = "Τάχιστη αλώπηξ βαφής ψημένη γη, δρασκελίζει υπέρ νωθρού κυνός";
$str = mb_convert_case($str, MB_CASE_UPPER, "UTF-8");
echo $str, PHP_EOL;
$str = mb_convert_case($str, MB_CASE_TITLE, "UTF-8");
echo $str, PHP_EOL;
?>

Notes

By contrast to the standard case folding functions such as strtolower() and strtoupper(), case folding is performed on the basis of the Unicode character properties. Thus the behaviour of this function is not affected by locale settings and it can convert any characters that have 'alphabetic' property, such a-umlaut (ä).

For more information about the Unicode properties, please see » http://www.unicode.org/reports/tr21/.

See Also