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using System;using System.Collections.Generic;using System.Text;namespace ConsoleApplication1{class Program{static void Main（string[] args）{// Create a new dictionary of strings, with string keys.//Dictionary<string, string> openWith =new Dictionary<string, string>（）;// Add some elements to the dictionary. There are no // duplicate keys, but some of the values are duplicates.openWith.Add（"txt", "notepad.exe"）;openWith.Add（"bmp", "paint.exe"）;openWith.Add（"dib", "paint.exe"）;openWith.Add（"rtf", "wordpad.exe"）;// The Add method throws an exception if the new key is // already in the dictionary.try{openWith.Add（"txt", "winword.exe"）;}catch （ArgumentException）{Console.WriteLine（"An element with 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["rtf"] = "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["doc"] = "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（"tif", out value））{Console.WriteLine（"For key = "tif", value = {0}.", value）;}else{Console.WriteLine（"Key = "tif" is not found."）;}// ContainsKey can be used to test keys before inserting // them.if （！openWith.ContainsKey（"ht"））{openWith.Add（"ht", "hypertrm.exe"）;Console.WriteLine（"Value added for key = "ht": {0}",openWith["ht"]）;}// When you use foreach to enumerate dictionary elements,// the elements are retrieved as KeyValuePair objects.Console.WriteLine（）;foreach （KeyValuePair<string, string> kvp in openWith）{Console.WriteLine（"Key = {0}, Value = {1}",kvp.Key, kvp.Value）;}// To get the values alone, use the Values property.Dictionary<string, 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<string, 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 （string s in keyColl）{Console.WriteLine（"Key = {0}", s）;}// Use the Remove method to remove a key/value pair.Console.WriteLine（"
Remove（"doc"）"）;openWith.Remove（"doc"）;if （！openWith.ContainsKey（"doc"））{Console.WriteLine（"Key "doc" is not found."）;}Console.ReadKey（）;}}}