$vowels = array("a", "e", "i", "o", "u", "A", "E", "I", "O", "U");
$onlyconsonants = str_replace($vowels, "", "Hello World of PHP");
// Fornece: Hll Wrld f PHP
<?php
$string = str_ireplace("FoX", "CAT", "the quick brown fox jumps over the lazy dog");
echo $string; // the quick brown CAT jumps over the lazy dog
?>