C#集合示例

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("/nRemove(/"doc/")");            openWith.Remove("doc");            if (!openWith.ContainsKey("doc"))            {                Console.WriteLine("Key /"doc/" is not found.");            }            Console.ReadKey();        }    }}