The strtoupper() function behaves identically in PHP 8.4 and PHP 8.5. There are no version-specific changes for this function in either release. The most recent behavioral change was in PHP 8.2.0, which made it locale-independent.
Function Overview
strtoupper() converts all ASCII alphabetic characters in a string to uppercase.
Syntax:
strtoupper(string $string): string
Example
<?php
$str = "Mary Had A Little Lamb and She LOVED It So";
$str = strtoupper($str);
echo $str;
// Outputs: MARY HAD A LITTLE LAMB AND SHE LOVED IT SO
?>