CODEWITHSUNDEEP
c#dictionarykey-value
Jakub Staněk
Jakub Staněk

Reputation: 1063

C# Dictionary get item by index

I am trying to make a method that returns a name of a card from my Dictionary randomly.

My Dictionary: First defined name of the card which is string and second is the value of that card, which is int.

public static Dictionary<string, int> _dict = new Dictionary<string, int>()
    {
        {"7", 7 },
        {"8", 8 },
        {"9", 9 },
        {"10", 10 },
        {"J", 1 },
        {"Q", 1 },
        {"K", 2 },
        {"A", 11 }
    };

Method: random is a randomly generated int.

    public string getCard(int random)
    {
        return Karta._dict(random);
    }

So the problem is:

Cannot convert from 'int' to 'string'

Anybody helps me how should I do it right to get the name?

Upvotes: 91

Views: 246450

Answers (5)

Hadi
Hadi

Reputation: 37313

If you need to extract an element key based on an index, this function can be used:

public string getCard(int random)
{
    return Karta._dict.ElementAt(random).Key;
}

If you need to extract the Key where the element value is equal to the integer generated randomly, you can use the following function:

public string getCard(int random)
{
    return Karta._dict.FirstOrDefault(x => x.Value == random).Key;
}

Make sure that you added reference to System.Linq in your class.

using System.Linq;

Side Note: The first element of the dictionary is The Key and the second is the Value

Upvotes: 135

B H
B H

Reputation: 1878

Is it useful to look beyond the exact question asked to alternatives that might better suit the need? Create your own class or struct, then make an array of those to operate on instead of being stuck with the operation of the KeyValuePair collection behavior of the Dictionary type.

Using a struct instead of a class will allow equality comparison of two different cards without implementing your own comparison code.

public struct Card
{
  public string Name;
  public int Value;

}

private int random()
{
  // Whatever
  return 1;
}

private static Card[] Cards = new Card[]
{
    new Card() { Name = "7", Value = 7 },
    new Card() { Name = "8", Value = 8 },
    new Card() { Name = "9", Value = 9 },
    new Card() { Name = "10", Value = 10 },
    new Card() { Name = "J", Value = 1 },
    new Card() { Name = "Q", Value = 1 },
    new Card() { Name = "K", Value = 1 },
    new Card() { Name = "A", Value = 1 }
};

private void CardDemo()
{
  int value, maxVal;
  string name;
  Card card, card2;
  List<Card> lowCards;

  value = Cards[random()].Value;
  name = Cards[random()].Name;
  card = Cards[random()];
  card2 = Cards[1];
  // card.Equals(card2) returns true
  lowCards = Cards.Where(x => x.Value == 1).ToList();
  maxVal = Cards.Max(x => x.Value);

}

Upvotes: 2

Noorul
Noorul

Reputation: 923

you can easily access elements by index , by use System.Linq

Here is the sample

First add using in your class file 

using System.Linq;

Then

yourDictionaryData.ElementAt(i).Key
yourDictionaryData.ElementAt(i).Value

Hope this helps.

Upvotes: 19

mybirthname
mybirthname

Reputation: 18127

You can take keys or values per index:

int value = _dict.Values.ElementAt(5);//ElementAt value should be <= _dict.Count - 1
string key = _dict.Keys.ElementAt(5);//ElementAt value should be  < =_dict.Count - 1

Upvotes: 61

Deepika Dixit
Deepika Dixit

Reputation: 131

Your key is a string and your value is an int. Your code won't work because it cannot look up the random int you pass. Also, please provide full code

Upvotes: 3

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