<!DOCTYPE html>
<html>
<body>
<?php
echo str_replace("world","Falguni","Hello world!");
?>
<p>In this example, we search for the string "Hello World!", find the value "world" and then replace the value with "Falguni".</p>
</body>
</html>
Hello Falguni!

In this example, we search for the string "Hello World!", find the value "world" and then replace the value with "Falguni".