how to make a word upper case in php code example

Example 1: php uppercase

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

Example 2: php uppercase each word

$upperCaseSentance=ucwords("i do not feel good");//I Do Not Feel Good