Hashtable in C#

Hashtable is used for store information based on key/value pairs. Hashtable class is defined in the System.Collections namespace.

Example: 

Form Design:

Sample form for hashtable example

Note:  You need to import two namespaces:

       using System;

     using System.Collections;

Code behind: 

        Hashtable ht = new Hashtable();

        private void Form1_Load(object sender, EventArgs e)

        {

           

            ht.Add("001", "computer");

            ht.Add("002", "laptop");

            ht.Add("003", "ipad 2");

            ht.Add("004", "ipad  3");

            ht.Add("005", "ipad 4");

            ht.Add("006", "iphone 4");

            ht.Add("007", "iphone 4s");

            ht.Add("008", "iphone 5");

            ht.Add("009", "sumsung galaxy S");

            ht.Add("010", "sumsung galaxy SI");

            ht.Add("011", "sumsung galaxy SII");

            ht.Add("012", "sumsung galaxy SIII");

            ICollection keys = ht.Keys;

            foreach (string ind in keys)

            {

                listBox1.Items.Add(ind + " : " + ht[ind]);

            }

        }

        private void button1_Click(object sender, EventArgs e)

        {

           //check whether the hashtable contain value : Sumsung Galaxy Tab

            if (ht.ContainsValue("Sumsung Galaxy Tab"))

            {

                label1.Text = "Sumsung Galaxy Tab is already in the list";

            }

            else

            {

                ht.Add("014", "Sumsung Galaxy Tab");

            }       

            //check whether the hashtable contain key : 013

            if (ht.ContainsKey("013"))

            {

                label2.Text = "013 is already in the list";

            }

            else

            {

                ht.Add("013", "Mac Book air");

            }                    

        }

Result:

Hope this post is helpful.