Determining Empty $_POST Value with Conditional Statements

The code provided performs a check to determine whether the $_POST['userName'] value exists and assigns it to the $username variable if present. However, it fails to accurately assign the default value of "Anonymous" when the value is empty.

To address this issue, it's crucial to use a more specific check that verifies not only the existence but also the actual content of the variable. In this case, using isset() is insufficient.

Solution: Trim and Test String Length

A better approach is to utilize the trim() function to remove any leading or trailing whitespace from the $_POST['userName'] value and then check its length. If the trimmed string is empty (i.e., with a length of 0), the $username variable can be safely set to "Anonymous." This can be achieved with the following code:

if("" == trim($_POST['userName'])){
    $username = 'Anonymous';
}      

By implementing this modification, the code will correctly set $username to "Anonymous" only when the $_POST['userName'] value is truly empty. This ensures proper handling of empty form field values while accurately assigning the specified default value.