Check if the Hashtable contains a specific Key in C#

To check if Hashtable contains a specific key, the code is as follows −

Example

using System;
using System.Collections;
public class Demo {
   public static void Main()
   public static void Main(){
      Hashtable hash = new Hashtable();
      hash.Add("One", "Katie");
      hash.Add("Two", "John");
      hash.Add("Three", "Barry");
      hash.Add("Four", "Mark");
      hash.Add("Five","Harry");
      hash.Add("Six", "Nathan");
      hash.Add("Seven", "Tom");
      hash.Add("Eight","Andy");
      hash.Add("Nine", "Illeana");
      hash.Add("Ten", "Tim");
      Console.WriteLine("Hashtable Key and Value pairs...");
      foreach(DictionaryEntry entry in hash){
         Console.WriteLine("{0} and {1} ", entry.Key, entry.Value);
      }
      Console.WriteLine("Is Hashtable having fixed size? = "+hash.IsFixedSize);
      Console.WriteLine("If Hashtable read-only? = "+hash.IsReadOnly);
      Console.WriteLine("The Hashtable consists of the key? = "+hash.ContainsKey("Seven"));
   }
}

Output

This will produce the following output −

Hashtable Key and Value pairs...
One and Katie
Ten and Tim
Five and Harry
Three and Barry
Seven and Tom
Two and John
Four and Mark
Eight and Andy
Nine and Illeana
Six and Nathan
Is Hashtable having fixed size? = False If Hashtable read-only? = False
The Hashtable consists of the key? = True

Example

Let us see another example −

 Live Demo

using System;
using System.Collections;
public class Demo {
   public static void Main(){
      Hashtable hash = new Hashtable();
      hash.Add("1", "A");
      hash.Add("2", "B");
      hash.Add("3", "C");
      hash.Add("4", "D");
      hash.Add("5","E");
      hash.Add("6", "F");
      hash.Add("7", "G");
      hash.Add("8","H");
      hash.Add("9", "I");
      hash.Add("10", "J");
      Console.WriteLine("Hashtable Key and Value pairs...");
      foreach(DictionaryEntry entry in hash){
         Console.WriteLine("{0} and {1} ", entry.Key, entry.Value);
      }
      Console.WriteLine("Is Hashtable having fixed size? = "+hash.IsFixedSize);
      Console.WriteLine("If Hashtable read-only? = "+hash.IsReadOnly);
      Console.WriteLine("The Hashtable consists of the key? = "+hash.ContainsKey("5"));
   }
}

Output

This will produce the following output −

Hashtable Key and Value pairs...
10 and J
1 and A
2 and B
3 and C
4 and D
5 and E
6 and F
7 and G
8 and H
9 and I
Is Hashtable having fixed size? = False If Hashtable read-only? = False
The Hashtable consists of the key? = True