php change sting to caps

1$lowercase = "this is lower case";
2$uppercase = strtoupper($lowercase);
3
4echo $uppercase;
5// THIS IS LOWER CASE

1<?php
2/* There is a function in php wich convert all string to uppercase */
3
4  echo strtoupper("Hello samy! how are u ?"); 
5
6// output :   HELLO SAMY! HOW ARE U ?
7?>

1$lowercase = "this is lower case";
2$uppercase = strtoupper($lowercase);
3
4echo $uppercase;