C# | Check if SortedDictionary contains the specified key or not

Last Updated : 11 Jul, 2025
SortedDictionary<TKey, TValue>.ContainsKey(TKey) Method is used to check whether the SortedDictionary contains an element with the specified key or not. Syntax: 
public bool ContainsKey (TKey key);
Here, the key is the Key which is to be located in the SortedDictionary. Returns 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 the above-discussed method: Example 1: csharp 
// C# code to check if a key is
// present or not in a SortedDictionary.
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

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

        // Adding key/value pairs in myDict
        myDict.Add(1, "C");
        myDict.Add(2, "C++");
        myDict.Add(3, "Java");
        myDict.Add(4, "Python");
        myDict.Add(5, "C#");
        myDict.Add(6, "HTML");

        // Checking for Key 4
        if (myDict.ContainsKey(4))
            Console.WriteLine("Key : 4 is present");

        else
            Console.WriteLine("Key : 4 is absent");
    }
}
Output: 
Key : 4 is present
Example 2: csharp 
// C# code to check if a key is
// present or not in a SortedDictionary.
using System;
using System.Collections.Generic;

class GFG {

    // Driver code
    public static void Main()
    {

        // Create a new dictionary of
        // strings, with string keys.
        SortedDictionary<string, string> myDict =
          new SortedDictionary<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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