A simple class for interacting with a deck of cards.

Cards.php

<?php

/**
 * Contains methods for interacting with a deck of cards.
 * 
 * @author Daniel Sposito <daniel.g.sposito@gmail.com>
 */
class Deck
{
    /**
	 * Builds a deck of cards.
	 *
	 * @return array
	 */
	public static function cards()
	{
		$values = array('2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K', 'A');
		$suits  = array('S', 'H', 'D', 'C');
		
		$cards = array();
		foreach ($suits as $suit) {
			foreach ($values as $value) {
				$cards[] = $value . $suit;
			}
		}
		
		return $cards;
	}
	
	/**
	 * Shuffles an array of cards.
	 *
	 * @param array $cards The array of cards to shuffle.
	 *
	 * @return array
	 */
	public static function shuffle(array $cards)
	{
		$total_cards = count($cards);
		
		foreach ($cards as $index => $card) {
			// Pick a random second card.
			$card2_index = mt_rand(1, $total_cards) - 1;
			$card2 = $cards[$card2_index];
			
			// Swap the positions of the two cards.
			$cards[$index] = $card2;
			$cards[$card2_index] = $card;
		}
		
		return $cards;
	}
}

$cards = Deck::cards();

echo "Cards: " . implode(', ', $cards);
echo "<br /><br />Shuffled Cards: " . implode(', ', Deck::shuffle($cards));

There is an issue with the shuffle function duplicating the first card - might be best to replace that function with a less random shuffle function.

I think it's because of the for foreach loop on a changing array.
This seems to work
for($index=0;$index<count($cards);$index++) { $card = $cards[$index]; ......... }