php string to uppercase

1//string to all uppercase
2$string = "String with Mixed use of Uppercase and Lowercase";
3//php string to uppercase
4$string = strtoupper($string);
5// = "STRING WITH MIXED USE OF UPPERCASE AND LOWERCASE"

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

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

1string strtoupper ( $string )
2

1$str = strtolower($str);

1<?php
2$str = "Mary Had A Little Lamb and She LOVED It So";
3$str = strtoupper($str);
4echo $str; // show: MARY HAD A LITTLE LAMB AND SHE LOVED IT SO