What role does the isset() function play in preventing unexpected behavior in PHP form processing?

The isset() function in PHP is used to check if a variable is set and is not null. When processing form data in PHP, using isset() can prevent unexpected behavior by ensuring that the form fields are set before trying to access their values. This helps prevent errors and warnings that may occur if a form field is not set or is empty.

if(isset($_POST['submit'])) {
    $name = isset($_POST['name']) ? $_POST['name'] : '';
    $email = isset($_POST['email']) ? $_POST['email'] : '';
    
    // Process the form data
}