if ($_POST['name'] == '' || $_POST['email'] == '') { echo 'Please enter your name and email.'; }
if (!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)) { echo 'Please enter a valid email address.'; }
$password = $_POST['password']; if (strlen($password) < 8) { echo 'Your password must be at least 8 characters long.'; } elseif (!preg_match("#[0-9]+#", $password)) { echo 'Your password must contain at least one number.'; } elseif (!preg_match("#[a-z]+#", $password)) { echo 'Your password must contain at least one lowercase letter.'; } elseif (!preg_match("#[A-Z]+#", $password)) { echo 'Your password must contain at least one uppercase letter.'; } elseif (!preg_match("#\W+#", $password)) { echo 'Your password must contain at least one symbol.'; }The package library for PHP validation checks is the PHP filter extension. This extension provides a collection of functions for filtering input data and validating user input.