Using mb_strtolower() to Convert Strings to Lowercase in PHP

mb_strtolower() is a PHP function that returns the input string with all alphabetic characters converted to lowercase.

Parameters: str – the string to be converted; encoding – optional character encoding, defaulting to the internal encoding if omitted.

Return value: the string with all alphabetic characters in lowercase.

Example 1:

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

Example 2 (UTF‑8):

<?php
$str = "Τ?χιστη αλ?πηξ βαφ?? ψημ?νη γη, δρασκελ?ζει υπ?ρ νωθρο? κυν??";
$str = mb_strtolower($str, 'UTF-8');
echo $str; // 输出 τ?χιστη αλ?πηξ βαφ?? ψημ?νη γη, δρασκελ?ζει υπ?ρ νωθρο? κυν??
?>