What is difference between ArrayList & Hashtable in C#?

C# - Difference between Hash Table and Arraylist?

In this article we will try to understand the difference between C# hastable and arraylist. So there are following difference between ArrayList and Hashtable :

• A hashtable store data as name, value pair. While an ArrayList only value is store.

• If you want to access value from the hashtable, you need to pass name. While in arraylist to access value, you need to pass index value.

Hashtable and Arraylist in C#

Hence the basic difference is that HashTable represents a collection of key/value pairs that are organized based on the hash code of the key. Each element is a key/value pair stored in a DictionaryEntry object. A key cannot be null, but a value can be. 

The ArrayList class implements a collection of objects using an array whose size is dynamically increased as required. The ArrayList class is very useful if you are working with arrays and need to add, remove, index, or search for data in a collection.

Let try to understand the difference between ArrayList and Hashtable with example in C#. Find the code below :-

Hastable Example C#

using System.Collections;

protected void Page_Load(object sender, EventArgs e)

    {

        Hashtable ht = new Hashtable();

        ht.Add("01", "Rk Singh");

        ht.Add("02", "Kunal");

        ht.Add("03", "Prashant");

        ht.Add("04", "Mohan");

        ht.Add("05", "Satya");

        

        if (ht.ContainsValue("Satya"))

        {

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

        }

        else

        {

            ht.Add("06", "Satya");

        }

        // Get a collection of the keys.

        ICollection key = ht.Keys;

        foreach (string k in key)

        {

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

        }       

    }

OutPut

Satya is already in the list

04: Mohan03: Prashant02: Kunal01: Rk Singh05: Satya [post_ad]

ArrayList Example

using System.Collections;

protected void Page_Load(object sender, EventArgs e)

    {

       ArrayList al = new ArrayList();

            Console.WriteLine("Adding some numbers:");

            al.Add(11);

            al.Add(42);

            al.Add(33);

            al.Add(21);

            al.Add(35);

            al.Add(46);

            al.Add(77);

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

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

                     

            Response.Write("Content: ");

            foreach (int i in al)

            {

                Response.Write(i + " ");

            }

           

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

            al.Sort();

            foreach (int i in al)

            {

                Response.Write(i + " ");

            }           

        }

Output

Capacity: {0}8

Count: {0}7
Content: 11 42 33 21 35 46 77
Sorted Content: 11 21 33 35 42 46 77 

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