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C# | Dictionary.ContainsKey() Method - GeeksforGeeks

C# | Dictionary.ContainsKey() Method

Last Updated : 11 Jul, 2025

This method is used to check whether the Dictionary<TKey,TValue> contains the specified key or not.

Syntax: 
public bool ContainsKey (TKey key);

Here, the

key

is the Key which is to be located in the Dictionary.

Return Value:

This method will return

true

if the Dictionary contains an element with the specified key otherwise, it returns

false

.

Exception:

This method will give

ArgumentNullException

if the key is null. Below are the programs to illustrate the use of

Dictionary<TKey,TValue>.ContainsKey() Method

:

Example 1: csharp 
// C# code to check if a key is 
// present or not in a Dictionary.
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Create a new dictionary of
        // strings, with string keys.
        Dictionary<string, string> myDict = 
          new Dictionary<string, string>();

        // Adding key/value pairs in myDict
        myDict.Add("Australia", "Canberra");
        myDict.Add("Belgium", "Brussels");
        myDict.Add("Netherlands", "Amsterdam");
        myDict.Add("China", "Beijing");
        myDict.Add("Russia", "Moscow");
        myDict.Add("India", "New Delhi");

        // Checking for Key "India"
        if (myDict.ContainsKey("India"))
            Console.WriteLine("Key : India is present");

        else
            Console.WriteLine("Key : India is absent");
    }
}
Output: 
Key : India is present
Example 2: csharp 
// C# code to check if a key is 
// present or not in a Dictionary.
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Create a new dictionary of 
        // strings, with string keys.
        Dictionary<string, string> myDict = 
           new Dictionary<string, string>();

        // Adding key/value pairs in myDict
        myDict.Add("Australia", "Canberra");
        myDict.Add("Belgium", "Brussels");
        myDict.Add("Netherlands", "Amsterdam");
        myDict.Add("China", "Beijing");
        myDict.Add("Russia", "Moscow");
        myDict.Add("India", "New Delhi");

        // Checking for Key "USA"
        if (myDict.ContainsKey("USA"))
            Console.WriteLine("Key : USA is present");

        else
            Console.WriteLine("Key : USA is absent");
    }
}
Output: 
Key : USA is absent
Reference:

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