What role does the variable $check play in the PHP script and how does its initialization affect the form validation logic?

The variable $check in the PHP script is used to store the result of form validation checks. Its initialization as true means that by default, the form is considered valid. If any validation check fails, $check is set to false, indicating that the form is invalid. This initialization affects the form validation logic by providing a starting point for checking the validity of the form inputs.

// Initialize $check as true for valid form by default
$check = true;

// Perform form validation checks
if(empty($_POST['username'])) {
    $check = false;
}

if(empty($_POST['password'])) {
    $check = false;
}

// If $check is still true after all validation checks, the form is valid
if($check) {
    // Process form data
    echo "Form submitted successfully!";
} else {
    // Display error message
    echo "Please fill in all required fields.";
}