# Shuffling an Array in C#

I was using `Arrays` as part of making a Blackjack game, which was a college assessment. I used multiple `Arrays` to create a deck of cards, see my other post "Creating a deck of cards in C#". But, now I needed to shuffle these cards, similar to how you would a normal deck of cards. I needed to find a way to mix this `Array` of cards up for the game to be more realistic.

## Shuffling the deck

To shuffle the cards in the deck I knew I would need to use a Random method to select the cards to shuffle, but after that, I drew a blank. Similar to when I researched about creating a deck, it showed the same results linked to `enum` and `list`. From the research, I learned that I would need to set up a temporary card, and then move the random card chosen between the temporary card and another card.

## How I shuffled my deck of cards…

In my code below, I created a card variable and set this to the first card in the deck. After this, I set up a for loop to run 720 (this can be anything, but should be a large number), within this loop I created a random card to choose within the length of the cards `Array` except for the first card in the `Array`, because this is the card we will change it to. As you can see, after the shuffle is set, the first card in the `Cards` `Array` has been set to the random card, the random card is then set to the variable(which has already been set at the beginning, to the `Cards` object at `index[0]`). This code then runs over the loop 720 times constantly swapping the first card to a random card in the deck.

```csharp
public void ShuffleDeck()
{
    for (int shuffleNum = 0; shuffleNum < 720; shuffleNum++)
    {
        // pick the first card
        ...

        // pick a card that's not the first card
        int shuffleCardIndex = randomCard.Next(1, Cards.Length);

        // swap the first card with the shuffle card
        Cards[0] = Cards[shuffleCardIndex];
        Cards[shuffleCardIndex] = firstCard;
    }
}
```

This method is then called in the `CreateDeck` method on the `Deck` object, so when a deck is created it is automatically shuffled.

```csharp
private Card[] CreateDeck()
 {
    ...

    ShuffleDeck();

    return Cards;
  }
```

Reference: [Defining your cards and deck](https://codereview.stackexchange.com/questions/273832/card-shuffle-without-using-any-help-c)