// http://svc.luckstar.com.tw/CodeHelper/cs/index.html
// 2017-03-26, honda@luckstar.com.tw, Create.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleBase
{
    public class CSortedDictionary
    {
        SortedDictionary<string, string> mList1 = new SortedDictionary<string, string>();
        public void Run()
        {
            Console.WriteLine("Basic of SortedDictionary:");

            // Add some elements to the dictionary. There are no 
            // duplicate keys, but some of the values are duplicates.
            mList1.Add("txt", "notepad.exe");
            mList1.Add("bmp", "paint.exe");
            mList1.Add("dib", "paint.exe");
            mList1.Add("rtf", "wordpad.exe");

            // The Add method throws an exception if the new key is 
            // already in the dictionary.
            try
            {
                mList1.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}.", mList1["rtf"]);

            // The indexer can be used to change the value associated
            // with a key.
            mList1["rtf"] = "winword.exe";
            Console.WriteLine("For key = \"rtf\", value = {0}.", mList1["rtf"]);

            // If a key does not exist, setting the indexer for that key
            // adds a new key/value pair.
            mList1["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}.", mList1["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 (mList1.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 (!mList1.ContainsKey("ht"))
            {
                mList1.Add("ht", "hypertrm.exe");
                Console.WriteLine("Value added for key = \"ht\": {0}", mList1["ht"]);
            }

            // When you use foreach to enumerate dictionary elements,
            // the elements are retrieved as KeyValuePair objects.
            Console.WriteLine();
            foreach (KeyValuePair<string, string> kvp in mList1)
            {
                Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);
            }

            // To get the values alone, use the Values property.
            SortedDictionary<string, string>.ValueCollection valueColl = mList1.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.
            SortedDictionary<string, string>.KeyCollection keyColl = mList1.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\")");
            mList1.Remove("doc");

            if (!mList1.ContainsKey("doc"))
            {
                Console.WriteLine("Key \"doc\" is not found.");
            }
        }
        private void PrintDashLine()
        {
            Console.WriteLine();
            Console.WriteLine("----------");
        }
    }
}

result:

Basic of SortedDictionary:
An element with Key = "txt" already exists.
For key = "rtf", value = wordpad.exe.
For key = "rtf", value = winword.exe.
Key = "tif" is not found.
Key = "tif" is not found.
Value added for key = "ht": hypertrm.exe

Key = bmp, Value = paint.exe
Key = dib, Value = paint.exe
Key = doc, Value = winword.exe
Key = ht, Value = hypertrm.exe
Key = rtf, Value = winword.exe
Key = txt, Value = notepad.exe

Value = paint.exe
Value = paint.exe
Value = winword.exe
Value = hypertrm.exe
Value = winword.exe
Value = notepad.exe

Key = bmp
Key = dib
Key = doc
Key = ht
Key = rtf
Key = txt

Remove("doc")
Key "doc" is not found.