Hash Table and Dictionary in C#

Dictionary

A Dictionary class represents a dictionary in C# that is used to represent a collection of keys and values pair of data. This article demonstrates how to use a dictionary in C#.

The Dictionary class is a generic class and can store any data types. This class is defined in the System.Collections.Generic namespace. Before you use a Dictionary class in your code, you must import the System.Collections.Generic namespace using the following line.

C#

using System.Collections.Generic;

VB.NET

Imports System.Collections.Generic

As other collection classes, the Dictionary class has Add, Remove, RemoveAt and other collection methods. The Key and Value property are used to extract a key and a value from an item in a Dictionary.

The following code snippet creates a Dictionary, adds some data to it and reads data back.

VB.NET Code:

Imports System.Collections.Generic

Module Module1

    Sub Main()

        Dim AuthorList As New Dictionary(Of String, Int16)
        AuthorList.Add("Mahesh Chand", 35)
        AuthorList.Add("Mike Gold", 25)
        AuthorList.Add("Praveen Kumar", 29)
        AuthorList.Add("Raj Beniwal", 21)
        AuthorList.Add("Dinesh Beniwal", 84)

        ' Read all data

        Console.WriteLine("Authors List")

        For Each author As KeyValuePair(Of String, Int16) In AuthorList
            Console.WriteLine("Key = {0}, Value = {1}", _
                author.Key, author.Value)
        Next author

        Console.ReadKey()

    End Sub

End Module

C# Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections.Generic;

namespace DictionarySample
{

    class Program
    {

        static void Main(string[] args)
        {           

            Dictionary<string, Int16> AuthorList = new Dictionary<string, Int16>();
            AuthorList.Add("Mahesh Chand", 35);
            AuthorList.Add("Mike Gold", 25);
            AuthorList.Add("Praveen Kumar", 29);
            AuthorList.Add("Raj Beniwal", 21);
            AuthorList.Add("Dinesh Beniwal", 84);

            // Read all data
            Console.WriteLine("Authors List");

            foreach( KeyValuePair<string, Int16> author in AuthorList )
            {
                Console.WriteLine("Key = {0}, Value = {1}",
                    author.Key, author.Value);
            }

            Console.ReadKey();

        }
    }
}