Normal parameter and params parameters

   
 

using System;

public class Starter {
    public static void Main() {
        Names("F", "F", "B", "A");
        Names("F", 1234, 5678, 9876, 4561);
        Names("F", "C", "D");
    }

    public static void Names(string company,params string[] employees) {
        Console.WriteLine("{0} employees: ",company);
        foreach (string employee in employees) {
            Console.WriteLine(" {0}", employee);
        }
    }

    public static void Names(string company,params int[] emplid) {
        Console.WriteLine("{0} employees: ",company);
        foreach (int employee in emplid) {
            Console.WriteLine(" {0}", employee);
        }
    }

    public static void Names(string company,string empl1, string empl2) {
        Console.WriteLine("{0} employees: ",company);
        Console.WriteLine("  {0}", empl1);
        Console.WriteLine("  {0}", empl2);
    }
}

    


Params Array

   
 

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

class Util {
    public static int Sum(params int[] paramList) {
        if (paramList == null) {
            throw new ArgumentException("Util.Sum: null parameter list");
        }

        if (paramList.Length == 0) {
            throw new ArgumentException("Util.Sum: empty parameter list");
        }

        int sumTotal = 0;
        foreach (int i in paramList) {
            sumTotal += i;
        }
        return sumTotal;
    }
}
class Program {
    static void Entrance() {
        Console.WriteLine(Util.Sum(10, 9, 8, 7, 6, 5, 4, 3, 2, 1));
    }

    static void Main() {
        try {
            Entrance();
        } catch (Exception ex) {
            Console.WriteLine("Exception: {0}", ex.Message);
        }
    }
}

    


Ref and Out Parameters 2


   


using System;
class Point
{
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    
    public void GetPoint(out int x, out int y)
    {
        x = this.x;
        y = this.y;
    }
    
    int x;
    int y;
}

public class RefOutParameters3
{
    public static void Main()
    {
        Point myPoint = new Point(10, 15);
        int x;
        int y;
        
        myPoint.GetPoint(out x, out y);
        Console.WriteLine("myPoint({0}, {1})", x, y);
    }
}

           
          


C# Ref and Out Parameters


   


using System;
class Point
{
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    
    public void GetPoint(ref int x, ref int y)
    {
        x = this.x;
        y = this.y;
    }
    
    int x;
    int y;
}

public class RefOutParameters2
{
    public static void Main()
    {
        Point myPoint = new Point(10, 15);
        int x = 0;
        int y = 0;
        
        myPoint.GetPoint(ref x, ref y);
        Console.WriteLine("myPoint({0}, {1})", x, y);
    }
}
           
          


Ref and Out Parameters: compiling error

   


// error
using System;
class Point
{
    public Point(int x, int y)
    {
        this.x = x;
        this.y = y;
    }
    // get both values in one function call
    public void GetPoint(ref int x, ref int y)
    {
        x = this.x;
        y = this.y;
    }
    
    int x;
    int y;
}

public class RefOutParameters {
    public static void Main()
    {
        Point myPoint = new Point(10, 15);
        int x;
        int y;
        
        // illegal 
        myPoint.GetPoint(ref x, ref y);
        Console.WriteLine("myPoint({0}, {1})", x, y);
    }
}
           
          


Pass value by reference with read only value


   

/*
Learning C# 
by Jesse Liberty

Publisher: O'Reilly 
ISBN: 0596003765
*/
 using System;

 namespace PassByRef
 {

     public class Time
     {
         // private member variables
         private int Year;
         private int Month;
         private int Date;
         private int Hour;
         private int Minute;
         private int Second;

         // Property (read only)
         public int GetHour()
         {
             return Hour;
         }

         // public accessor methods
         public void DisplayCurrentTime()
         {
             System.Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}",
                 Month, Date, Year, Hour, Minute, Second);
         }

         // takes references to ints
         public void GetTime(ref int h, ref int m, ref int s)
         {
             h = Hour;
             m = Minute;
             s = Second;
         }

         // constructor
         public Time(System.DateTime dt)
         {

             Year = dt.Year;
             Month = dt.Month;
             Date = dt.Day;
             Hour = dt.Hour;
             Minute = dt.Minute;
             Second = dt.Second;
         }


     }

    public class TesterPassByRef
    {
       public void Run()
       {
           System.DateTime currentTime = System.DateTime.Now;
           Time t = new Time(currentTime);
           t.DisplayCurrentTime();

           int theHour = 0;
           int theMinute = 0;
           int theSecond = 0;

           // pass the ints by reference
           t.GetTime(ref theHour, ref theMinute, ref theSecond);

           System.Console.WriteLine("Current time: {0}:{1}:{2}",
               theHour, theMinute, theSecond);

       }

       static void Main()
       {
          TesterPassByRef t = new TesterPassByRef();
          t.Run();
       }
    }
 }

           
          


Pass value by reference


   

/*
Learning C# 
by Jesse Liberty

Publisher: O'Reilly 
ISBN: 0596003765
*/
 using System;

 namespace PassByRef
 {

     public class Time3
     {
         // private member variables
         private int Year;
         private int Month;
         private int Date;
         private int Hour;
         private int Minute;
         private int Second;

         // Property (read only)
         public int GetHour()
         {
             return Hour;
         }

         // public accessor methods
         public void DisplayCurrentTime()
         {
             System.Console.WriteLine("{0}/{1}/{2} {3}:{4}:{5}",
                 Month, Date, Year, Hour, Minute, Second);
         }

         public void GetTime(int h, int m, int s)
         {
             h = Hour;
             m = Minute;
             s = Second;
         }

         // constructor
         public Time3(System.DateTime dt)
         {

             Year = dt.Year;
             Month = dt.Month;
             Date = dt.Day;
             Hour = dt.Hour;
             Minute = dt.Minute;
             Second = dt.Second;
         }


     }

    public class PassByRefTester
    {
       public void Run()
       {
           System.DateTime currentTime = System.DateTime.Now;
           Time3 t = new Time3(currentTime);
           t.DisplayCurrentTime();

           int theHour = 0;
           int theMinute = 0;
           int theSecond = 0;
           t.GetTime(theHour, theMinute, theSecond);
           System.Console.WriteLine("Current time: {0}:{1}:{2}",
               theHour, theMinute, theSecond);

       }

       static void Main()
       {
          PassByRefTester t = new PassByRefTester();
          t.Run();
       }
    }
 }