PHP mb_strtolower() Function

22 June 2025

2

The mb_strtolower() is a PHP inbuilt function that returns lowercase alphanumeric characters.

Syntax:

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

Parameters: This function accepts 2 parameters:

string: This parameter specifies the lowercase string.
encoding: This parameter denotes the character encoding, & in case omitted or null, then the internal character encoding value will be utilized.

Return value: This function converted the uppercase string into lowercase alphanumeric characters and then returns those characters.

Example 1: The following code shows the working for the mb_strtolower() function.

PHP

<?php
$str = "GEEKSFORGEEKS" ;
$str2 = mb_strtolower($str);
echo $str2; 
?>

Output:

neveropen

Example 2: The following code shows the working for the mb_strtolower() function.

<?php
$str = "Dmmm" ;
$str2 = mb_strtolower($str);
echo $str2; 
?>

Output:

dmmm

Reference: https://www.php.net/manual/en/function.mb-strtolower.php