Check whether a Hashtable contains a specific key or not in C#

To check whether a Hashtable contains a specific key or not, the code is as follows −

Example

 Live Demo

using System; using System.Collections; public class Demo {    public static void Main(){       Hashtable hash = new Hashtable();       hash.Add("One", "Katie");       hash.Add("Two", "John");       hash.Add("Three", "Barry");       hash.Add("Four", "");       hash.Add("Five","Harry");       hash.Add("Six", "F");       hash.Add("Seven", "Tom");       hash.Add("Eight","Andy");       hash.Add("Nine", "I");       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 the Hashtable having fixed size? = "+hash.IsFixedSize);       Console.WriteLine("If Hashtable read-only? = "+hash.IsReadOnly);       Hashtable hash2 = Hashtable.Synchronized(hash);       Console.WriteLine("Is Hash synchronized = "+hash2.IsSynchronized);       Console.WriteLine("Does Hashtable contains the key Ten = "+hash.Contains("Ten"));    } }

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 Eight and Andy Nine and I Six and F Is the Hashtable having fixed size? = False If Hashtable read-only? = False Is Hash synchronized = True Does Hashtable contains the key Ten = True

Example

Let us now see another example −

 Live Demo

using System; using System.Collections; public class Demo {    public static void Main(){       Hashtable hash = new Hashtable();       hash.Add("1", "AB");       hash.Add("2", "BC");       hash.Add("3", "DE");       hash.Add("4", "EF");       hash.Add("5", "GH");       hash.Add("6", "IJ");       hash.Add("7", "KL");       hash.Add("8", "MN");       hash.Add("9", "OP");       hash.Add("10", "QR");       Console.WriteLine("Value at key 3 = "+hash["3"]);       Console.WriteLine("Does Hashtable contains the key 12 = "+hash.Contains("12"));    } }

Output

This will produce the following output −

Value at key 3 = DE Does Hashtable contains the key 12 = False