ContainsKey() method in C#

Set a Hashtable collection and add some elements to it.

Hashtable h = new Hashtable();
h.Add(1, "Sam");
h.Add(2, "Jack");
h.Add(3, "Andy");
h.Add(4, "Katie");
h.Add(5, "Beth");
h.Add(6, "Benjamin");

Use the ContainsKey() method to check whether a key exists in a Hashtable or not.

Let’s check for key 3. It returns True of the key is found.

h.ContainsKey(3));

Example

 Live Demo

using System;
using System.Collections;
public class Demo {
   public static void Main() {
      Hashtable h = new Hashtable();
      h.Add(1, "Sam");
      h.Add(2, "Jack");
      h.Add(3, "Andy");
      h.Add(4, "Katie");
      h.Add(5, "Beth");
      h.Add(6, "Benjamin");
      Console.WriteLine("Keys and Values list:");
      foreach (var key in h.Keys ) {
         Console.WriteLine("Key = {0}, Value = {1}",key , h[key]);
      }
      Console.WriteLine("Does the specified key exist? "+h.ContainsKey(3));
   }
}

Output

Keys and Values list:
Key = 6, Value = Benjamin
Key = 5, Value = Beth
Key = 4, Value = Katie
Key = 3, Value = Andy
Key = 2, Value = Jack
Key = 1, Value = Sam
Does the specified key exist? True