In PHP, to validate and sanitize external input filters are used. filter_var() function is used which perform both validate and sanitize external input. It takes two parameter:

• variable: It specify the variable you want to check.
• type: It specify the type to check

Syntax:

filter_var(variable, type)

Validate an Integer

For example:

<?php
$num = 500;

if (!filter_var($num, FILTER_VALIDATE_INT) === false) {
    echo("Integer is valid");
} else {
    echo("Integer is not valid");
}
?>

Sanitize and Validate an Email Address:

For example:

<?php
$email = "demo.test@demo.com";

// Remove 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");
}
?>