PHP Manual: mb_strtolower

Description

function mb_strtolower(string $string, ?string $encoding = null): string

Returns string with all alphabetic characters converted to lowercase.

Parameters

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

Return Values

string with all alphabetic characters converted to lowercase.

Errors/Exceptions

As of PHP 8.0.0, a ValueError is thrown if encoding is an invalid encoding. Prior to PHP 8.0.0, an E_WARNING was emitted instead.

Changelog

Version	Description
8.3.0	Implemented conditional casing rules for the Greek letter sigma.
8.0.0	Now throws a ValueError if `encoding` is an invalid encoding. Previously, an `E_WARNING` was emitted and `false` was returned.

Examples

Example #1 mb_strtolower() example

<?php
$str = "Mary Had A Little Lamb and She LOVED It So";
$str = mb_strtolower($str);
echo $str; // Prints mary had a little lamb and she loved it so
?>

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

<?php
$str = "Τάχιστη αλώπηξ βαφής ψημένη γη, δρασκελίζει υπέρ νωθρού κυνός";
$str = mb_strtolower($str, 'UTF-8');
echo $str; // Prints τάχιστη αλώπηξ βαφής ψημένη γη, δρασκελίζει υπέρ νωθρού κυνός
?>

Notes

By contrast to strtolower(), 'alphabetic' is determined by 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 as a-umlaut (ä).

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

mb_strtolower