using System;

using System.Collections.Generic;

​

namespace keyvalue{

  public class program{

​

public static void Main(string[] args)

{

Dictionary<int, string> openWith =  new Dictionary<int, string>();

​

// Add some elements to the dictionary. There are no

// duplicate keys, but some of the values are duplicates.

openWith.Add(2, "notepad.exe");

openWith.Add(4, "paint.exe");

openWith.Add(6, "paint.exe");

openWith.Add(8, "wordpad.exe");

​

// The Add method throws an exception if the new key is

// already in the dictionary.

try

{

    openWith.Add(8, "winword.exe");

}

catch (ArgumentException)

{

 //   Console.WriteLine("An element with the Key = \"txt\" already exists.");

}

​

// The Item property is another name for the indexer, so you

// can omit its name when accessing elements.

//Console.WriteLine("For key = \"rtf\", value = {0}.",

//    openWith["rtf"]);

​

// The indexer can be used to change the value associated

// with a key.

openWith[8] = "winword.exe";

//Console.WriteLine("For key = \"rtf\", value = {0}.",

//    openWith["rtf"]);

​

// If a key does not exist, setting the indexer for that key

// adds a new key/value pair.

openWith[9] = "winword.exe";

​

// The indexer throws an exception if the requested key is

// not in the dictionary.

try

{

//    Console.WriteLine("For key = \"tif\", value = {0}.",

 //       openWith["tif"]);

}

catch (KeyNotFoundException)

{

    Console.WriteLine("Key = \"tif\" is not found.");

}

​

// When a program often has to try keys that turn out not to

// be in the dictionary, TryGetValue can be a more efficient

// way to retrieve values.

 string value ;

if (openWith.TryGetValue(2, out value))

{

   Console.WriteLine("For key = 2, value = {0}.", value);

}

else

{

    //Console.WriteLine("Key = \"tif\" is not found.");

}

​

// ContainsKey can be used to test keys before inserting

// them.

if (!openWith.ContainsKey(12))

{

    openWith.Add(12, "hypertrm.exe");

    Console.WriteLine("Value added for key = \"ht\": {0}",

        openWith[12]);

}

​

// When you use foreach to enumerate dictionary elements,

// the elements are retrieved as KeyValuePair objects.

Console.WriteLine();

foreach( KeyValuePair<int, string> kvp in openWith )

{

    Console.WriteLine("Key = {0}, Value = {1}",

        kvp.Key, kvp.Value);

}

​

// To get the values alone, use the Values property.

Dictionary<int, string>.ValueCollection valueColl =

    openWith.Values;

​

// The elements of the ValueCollection are strongly typed

// with the type that was specified for dictionary values.

Console.WriteLine();

foreach( string s in valueColl )

{

    Console.WriteLine("Value = {0}", s);

}

​

// To get the keys alone, use the Keys property.

Dictionary<int, string>.KeyCollection keyColl =

    openWith.Keys;

​

// The elements of the KeyCollection are strongly typed

// with the type that was specified for dictionary keys.

Console.WriteLine();

foreach( int s  in keyColl )

{

    Console.WriteLine("Key = {0}", s);

}

​

// Use the Remove method to remove a key/value pair.

Console.WriteLine("\nRemove(\"doc\")");

openWith.Remove(4);

​

if (!openWith.ContainsKey(4))

{

    Console.WriteLine("Key \"doc\" is not found.");

}

}

  }

  }