PHP strtolower() Function

The strtolower() function is used to convert a string into lowercase. This function takes a string as parameter and converts all the uppercase english alphabets present in the string to lowercase. All other numeric characters or special characters in the string remains unchanged.

Syntax:

string strtolower( $string )

Parameters: The only parameter to this function is a string that is to be converted to lower case.

Return value: This function returns a string in which all the alphabets are lower case.

Examples:

Input : $str  = "GeeksForGeeks"
        strtolower($str)
Output: geeksforgeeks

Input : $str  = "going BACK he SAW THIS 123$#%"
        strtolower($str)
Output: going back he saw this 123$#%

Below programs illustrate the strtolower() function in PHP:

Program 1:

<?php

// Original string
$str = "GeeksForGeeks";

// String converted to lower case
$resStr = strtolower($str);

print_r($resStr);

?>

Output:

geeksforgeeks

Program 2:

<?php

// Original string
$str = "going BACK he SAW THIS 123$#%";

// String converted to lower case
$resStr = strtolower($str);

print_r($resStr);

?>

Output:

going back he saw this 123$#%

PHP is a server-side scripting language designed specifically for web development. You can learn PHP from the ground up by following this PHP Tutorial and PHP Examples.