I created a form that the user can type first and last name. The result should be replace letter "s" with "5".
The form page code:
<form action="form.php" method="post">
First Name: <input type="text" name="firstname"><br>
Last Name: <input type="text" name="lastname"><br>
<input type="submit">
</form>
The result page code:
<?php
echo $_POST= str_replace("s","5",$_POST);
?>