Sams Teach Yourself PHP in 24 Hours, Third Edition

Using Hidden Fields to Save State

The script in Listing 10.7 has no way of knowing how many guesses a user has made. We can use a hidden field to keep track of this. The mark-up for a hidden field is similar to that of a text field. From the user’s perspective, however, it has no output. A user cannot see a hidden field, unless he views the HTML source of the document that contains it. Listing 10.8 adds a hidden field to the number-guessing script and some PHP to work with it.

Listing 10.8. Saving State with a Hidden Field

1: <?php 2: $num_to_guess = 42; 3: $message = ""; 4: if ( ! isset( $_POST['guess'] ) ) { 5: $message = "Welcome to the guessing machine!"; 6: } else if ( $_POST['guess'] > $num_to_guess ) { 7: $message = $_POST['guess']." ...