C# - SPLessons

How to use C# Dictionary Class

SPLessons 5 Steps, 3 Clicks
5 Steps - 3 Clicks

How to use C# Dictionary Class

How to use C# Dictionary Class

Description :

Hi Friends, let me give you a intro about “Dictionary”. It is a collection of keys and values pair of data.

It has two parameters which are  :

TKey – Define the type of the keys in the dictionary.

TValue – Define the type of the values in the dictionary.

Now we will see How to use C# Dictionary Class.

Namespace :


using System.Collections.Generic;

Step1 :

Please open visual studio, right now i have visual studio 2013 i just opened my visual studio and click on new project.

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons1.jpg[/image]

Step2 :

In the new project window please click on templates visual c# and then click on windows  and on the right side panel just click on console application. Please give a name for the console application and click ok button.

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons2.jpg[/image]

Step3 :

If you see the visual studio will gives you a predefined template program  for us.

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons3.jpg[/image]

Step4 :

Lets, Build simple console application to Insert, Delete, Search with key, Get all keys and  Display items from Dictionary.

Main Method :


public static Dictionary<string, string> dictionarytable = new Dictionary<string, string>();
public static Boolean flag = true;
static void Main(string[] args)
{
while (flag)
{
Console.WriteLine("\n1. Insert \t\t2. Remove \n3. Search with Key \t4. Get only Keys\n5. Display\t\t6. Exit");
Console.Write("Please enter your Choice: ");
string choice = Console.ReadLine();
switch (choice)
{
case "1":
dictionarytable = Insert(dictionarytable);
break;
case "2":
dictionarytable = Remove(dictionarytable);
break;
case "3":
FindValueUsingKey(dictionarytable);
break;
case "4":
GetKeysInList(dictionarytable);
break;
case "5":
Display(dictionarytable);
break;
case "6":
flag = false;
break;
default:
Console.WriteLine("Enter correct choice !!");
break;
}
}
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons4.jpg[/image]

Insert :


private static Dictionary<string, string> Insert(Dictionary<string, string> dictionarytable)
{
Console.Write("Please enter data into Dictionary Table.\nKey : ");
string key = Console.ReadLine();
Console.Write("Value : ");
string value = Console.ReadLine();
dictionarytable.Add(key, value);
Display(dictionarytable);
return dictionarytable;
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons5.jpg[/image]

Delete :


private static Dictionary<string, string> Remove(Dictionary<string, string> dictionarytable)
{
Console.Write("Please enter key of value to remove it from Dictionary Table.\nKey : ");
string key = Console.ReadLine();
dictionarytable.Remove(key);
Display(dictionarytable);
return dictionarytable;
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons6.jpg[/image]

Search with Key :


private static void FindValueUsingKey(Dictionary<string, string> dictionarytable)
{
Console.Write("Please enter key of value in the Dictionary Table.\nKey : ");
string key = Console.ReadLine();
bool status = dictionarytable.ContainsKey(key);
if(status)
{
Console.WriteLine(key + " with " + dictionarytable[key] + " is there in Dictionary Table.");
}
else
{
Console.WriteLine(key + " don't have any value.");
}
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons7.jpg[/image]

Get all Keys :


private static void GetKeysInList(Dictionary<string, string> dictionarytable)
{
Console.WriteLine("Keys in Dictionary Table :");
Dictionary<String, String>.KeyCollection keys = dictionarytable.Keys;
foreach(string item in keys)
{
Console.WriteLine(item);
}
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons8.jpg[/image]

Display :


private static void Display(Dictionary<string, string> dictionarytable)
{
Console.WriteLine("Item in Dictionary Table :");
foreach(KeyValuePair<string,string> item in dictionarytable)
{
Console.WriteLine(item.Key + "\t: " + item.Value);
}
}

Output :

[image url=””]/wp-content/uploads/2014/09/Dictionary-csharp-Splessons9.jpg[/image]

Other Methods :

There are many other methods which you can try.


Count :
Gets the number of elements contained in the Dictionary.


ContainsValue :
Determines whether the Dictionary  contains a specific value.


ValueCollection :
Represents the collection of values in a Dictionary.


TryGetValue :
Gets the value associated with the specified key.


Linq Operation :
We can perform lambda expressions like Join, etc. on Dictionary
etc.

Enjoy to Code..;)