Dictionary in C#

Syntax

The first argument specifies the key type and the second is for the value type.

Dictionary <dataType, dataType> dictionary = new Dictionary<dataType, dataType>();

Remember: Dictionary collection is implemented in the class System.Collection.Generics.

Basic methods

Method	Description
1.`Add(key, value)`	Used to insert a key-value pair in a dictionary.
2.`Remove(key)`	Used to remove a pair with a specified key.
3.`ConatinsKey(key)`	Used to check whether or not a specified key exists in the dictionary.
4.`ConatinsValue(value)`	Used to check whether or not a specified value exists in the dictionary.
5.`Clear()`	Used to remove all the pairs from the dictionary.

using System; 
using System.Collections.Generic; 
class DictionaryTesting
{
    static void Main()
    {
        Dictionary<int, string> dictionary = new Dictionary<int, string>();
        // Add(key, value) Method
        dictionary.Add(1,"John");
        dictionary.Add(2,"Cassy");
        dictionary.Add(3,"Peter");
        dictionary.Add(4,"Luis");
        dictionary.Add(5,"Flash");
        // Printing dictionary
        System.Console.WriteLine("Dictionary after adding pair:");
        foreach(KeyValuePair<int, string> temp in dictionary) 
          { 
            Console.WriteLine("Key {0} and Value {1}", temp.Key, temp.Value); 
          }
        
        // Remove(key) Method
        dictionary.Remove(4);        
        
        // Printing dictionary
        System.Console.WriteLine("Dictionary after removing pair with key 4:");
        foreach(KeyValuePair<int, string> temp in dictionary) 
          { 
            Console.WriteLine("Key {0} and Value {1}", temp.Key, temp.Value); 
          }
        // ConatinsKey(key) Method
        System.Console.WriteLine("Dictionary has any pair with the key = 5?");
        System.Console.WriteLine(dictionary.ContainsKey(5));
    }
}

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