PHP: Validate Vars

valid.php

<?php
// Check Range of Value
$value = filter_input(INPUT_GET, "value", FILTER_VALIDATE_INT,
    array("options" => array("min_range" => 15, "max_range" => 20)));
if ($value) {
    // run my code
}
else {
    // handle the issue
}

// Validate Email 
$email = filter_var($email, FILTER_VALIDATE_EMAIL);
if ($email !== false) {
	mail($email, "Here is my email", "Some Content");
}
else {
	// handle the issue invalid email address
}