Difference between Array List and Hash Table

Hash table

1.  Hash table is collection of key value pairs.
2.  Each element is key value pair and stored in a DictionaryEntry object.
3.  A value can be null but a key cannot be null.
4.  In hash table we access elements by keys.

Hastable Example

using System.Collections;

protected void Page_Load(object sender, EventArgs e)

    {

        Hashtable htable = new Hashtable();

        htable .Add("01", "Tejpal");

        htable .Add("02", "Bhavnish");

        htable .Add("03", "Prince");

        htable .Add("04", "Sandu");

        htable .Add("05", "Kiran");

        

        if (htable .ContainsValue("Tejpal"))

        {

            Response.Write("Tejpal is already in the list.<br/><br/>");

        }

        else

        {

            htable .Add("06", "Tejpal");

        }

        // Get a collection of the keys.

        ICollection key = htable .Keys;

        foreach (string k in key)

        {

            Response.Write(k + ": " + htable [k]);

        }       

    }

OutPut

Tejpal is already in the list

04: Sandu  03: Prince 02: Sandu 01: Tejpal 05: kiran

Array List

1. Array list is a collection of objects in array whose size can be dynamically increased according  to the requirement.
2. In array list we can add data of any data type, Every item in  array list is treated as object.
3. In array list we can access elements by using index.

ArrayList Example

using System.Collections;

protected void Page_Load(object sender, EventArgs e)

    {

       ArrayList arrLst = new ArrayList();

            Console.WriteLine("Adding numbers:");

            arrLst l.Add(21);

            arrLst .Add(23);

            arrLst .Add(45);

            arrLst .Add(22);

            arrLst .Add(56);

            arrLst .Add(47);

            arrLst .Add(37);

            Response.Write("Capacity: {0}" + arrLst .Capacity + "<br/>");

            Response.Write("Count: {0}" + arrLst .Count + "<br/>");

                     

            Response.Write("Content: ");

            foreach (int i in arrLst )

            {

                Response.Write(i + " ");

            }

           

            Response.Write("<br/>Sorted Content is: ");

            arrLst.Sort();

            foreach (int i in arrLst )

            {

                Response.Write(i + " ");

            }           

        }

Output

Capacity: {0}8

Count: {0}7
Content: 21 23 45 22 56 47 37
Sorted Content: 21 22 23 37 45 47 56