PHP Cookbook

4.21. Shuffling a Deck of Cards

Problem

You want to shuffle a deck of cards and deal them out.

Solution

Create a array of 52 integers, shuffle them, and map them to cards:

$suits = array('Clubs', 'Diamonds', 'Hearts', 'Spades');
$cards = array('Ace', 2, 3, 4, 5, 6, 7, 8, 9, 10, 'Jack', 'Queen', 'King');

$deck = pc_array_shuffle(range(0, 51));

while (($draw = array_pop($deck)) != NULL) {
    print  $cards[$draw / 4] . ' of ' . $suits[$draw % 4] . "\n";
}

This code uses the pc_array_shuffle( ) function from Recipe 4.21.

Discussion

Here, a pair of arrays, $suits and $cards, is created to hold the English representation of a card. The numbers 0 through 51 are randomly arranged and assigned to $deck. To deal a card, just pop them off the top of the array, treating the array like a literal deck of cards.

It’s necessary to add the check against NULL inside the while, otherwise the loop terminates when you draw the zeroth card. If you modify the deck to contain the numbers 1 through 52, the mathematics of deciding which number belongs to which card becomes more complex.

To deal multiple cards at once, call array_slice( ):

array_slice($deck, $cards * -1);

See Also

Recipe 4.21 for a function that randomizes an array; documentation on array_slice( ) at http://www.php.net/array-slice.