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Using Hidden Fields to Save State

The script in Listing 9.6 has no way of knowing how many guesses a user has made, but we can use a hidden field to keep track of this. A hidden field behaves exactly the same as a text field, except that the user cannot see it unless he views the HTML source of the document that contains it. Listing 9.7 adds a hidden field to the number-guessing script and some PHP to work with it.

Listing 9.7. Saving State with a Hidden Field

1: <?php 2: $num_to_guess = 42; 3: $num_tries = (isset($_POST[num_tries])) ? $num_tries + 1 : 0; 4: $message = ""; 5: if (!isset($_POST[guess])) { 6: $message = "Welcome to the guessing machine!"; 7: } else if ($_POST[guess] > $num_to_guess) { 8: $message = "$_POST[guess] is too big! Try ...