How to convert a String to Lowercase in PHP?

Converting a string to lowercase in PHP is a common operation that allows you to standardize string formats or perform case-insensitive comparisons.

Using strtolower() function:

PHP strtolower() converts all alphabetic characters in a string to lowercase.

$string = "GeeksForGeeks";
$lowercaseString = strtolower($string);
echo "Lowercase using strtolower(): $lowercaseString";

Using mb_strtolower() function

PHP mb_strtolower() performs case folding on a string, allowing accurate lowercase conversion for multibyte encodings like UTF-8.

$string = "GeeksForGeeks";
$lowercaseString = mb_strtolower($string, 'UTF-8');
echo "Lowercase using mb_strtolower(): $lowercaseString";

Using str_replace( ) function

PHP str_replace() method replaces each uppercase character in the string with its corresponding lowercase character using str_replace( ).

$string = "GeeksForGeeks";
$lowercaseString = str_replace(range('A', 'Z'), range('a', 'z'), $string);
echo "Lowercase using str_replace(): $lowercaseString";

Using Loop

This approach involves iterating through each character in the string and converting it to lowercase using strtolower().

$lowercaseString = '';
for ($i = 0; isset($string[$i]); $i++) {
    $lowercaseString .= strtolower($string[$i]);
}