Example of a C # collection

Using System;
Using System.Collections.Generic;
Using System.Text; Namespace ConsoleApplication1 {class Program {static void Main (string[] args) {//C
            Reate 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 a 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 is another name for the indexer and so I/can omit its name when accessing elements.
            Console.WriteLine ("For key = \ rtf\", value = {0}. ", openwith[" RTF "]);
            The indexer can is used to change the value associated//with a key.
            Openwith["rich-text"] = "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 a exception if the requested key is//isn't 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 is not to//is in the dictionary, TryGetValue can be a mor
            e 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 your 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}, V Alue = {1} ", kvp. Key, kvp.
            Value);
            }//To get the values alone and use the Values property. Dictionary<string, String>
            ValueCollection valuecoll = openwith.values; The elements of the valuecollection are strongly typed//with the type this is specified for dictionary V
            Alues.
            Console.WriteLine ();
            foreach (string s in Valuecoll) {Console.WriteLine ("Value = {0}", s);
            //To get the keys alone and use the keys. Dictionary<string, String>
            KeyCollection keycoll = Openwith.keys; The elements of the keycollection are strongly typed//with the type is 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 (); }
    }
}