C#

K1, AAA
K2, BBB
K3, BBB
K4, CCC

using System;
using System.Collections.Generic;

namespace KeyValuePair
{
    class Program
    {
        static void Main(string[] args)
        {
            List<KeyValuePair<string, string>> listImport = new List<KeyValuePair<string, string>>();
            listImport.Add(new KeyValuePair<string, string>("K1", "CCC"));
            listImport.Add(new KeyValuePair<string, string>("K2", "BBB"));
            listImport.Add(new KeyValuePair<string, string>("K3", "AAA"));
            listImport.Add(new KeyValuePair<string, string>("K4", "BBB"));
            listImport.Sort(delegate(KeyValuePair<string, string> first, KeyValuePair<string, string> second)
            {
                return first.Value.CompareTo(second.Value);
            });

            // We only need to "remember" the last value because the KeyValuePair list is sorted.
            string strLast = String.Empty;
            List<string> listDistinct = new List<string>();
            foreach (KeyValuePair<string, string> kvp in listImport)
            {
                if (strLast == kvp.Value)
                    continue;

                listDistinct.Add(kvp.Value);
                strLast = kvp.Value;
            }

            foreach (string str in listDistinct)
                Console.WriteLine(str);

            Console.ReadKey();
        }
    }
}

public class Form2 : Form
{
  private int m_nValue = 0;
  //Constructor
  public Form2()
  {
  }

  public void SetValue(int val)
  {
    m_nValue = val;
  }
}

Form2 frm = new Form2();
frm.SetValue(1);

internal class Form2 : Form
{
  internal Form2(MyClass obj) //define a constructor that takes MyClass as an argument
  {
    MessageBox.Show (obj.Name + " " + obj.Number); //use members of MyClass as you please..
  }
}

internal class MyClass
{
  internal string Name
  { get; set; }

  internal int Number
  { get; set; }
}

MyClass myC = new MyClass();
myC.Name = "John Doe";
myC.Number = 42;

Form2 f2 = new Form2(myC);
f2.Show();

serialPort1.DataReceived += new SerialDataReceivedEventHandler(serialPort1_DataReceiver);
     serialPort1.Open();
     string answer;
     serialPort1.Write("ATM2\r");
     answer = serialPort1.ReadLine();          //answer = "\r"
     serialPort1.Write("ATL3\r");
     answer = serialPort1.ReadLine();          //answer = "OK\r"
     serialPort1.Write("ATDT" + phone + "\r");
     answer = serialPort1.ReadLine();          //answer = "\r"
     serialPort1.Write("ATH\r");
     answer = serialPort1.ReadLine();          //answer = "OK\r"
     serialPort1.Close();