This PHP filters is used to validate and filter data coming from insecure sources, like user input. PHP 5.2

php-sanitize.php

<?php
// Reference: http://www.w3schools.com/php/php_ref_filter.asp
$bool = filter_var($bool, FILTER_VALIDATE_BOOLEAN);
$email = filter_var($email, FILTER_SANITIZE_EMAIL);
$newstr = filter_var($str, FILTER_SANITIZE_STRING);
$url = filter_var($var, FILTER_SANITIZE_URL);

// Example: Mail validation
$email = "john.doe@example.com";
// Remove all illegal characters from email
$email = filter_var($email, FILTER_SANITIZE_EMAIL);
// Validate e-mail
if (!filter_var($email, FILTER_VALIDATE_EMAIL) === false) {
    echo("$email is a valid email address");
} else {
    echo("$email is not a valid email address");
}