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Writing Hello World in different styles using C# and .NET

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11 Jan 2004 134.9K   32   16
Writing Hello World in different styles using C# and .NET

Introduction

I’ve attempted to write the traditional ‘Hello World’ in different styles. This explores the different possibilities of addressing a problem – ‘Hello World’ with different features of the C# language and the .NET framework.

The implementations

1. A Beginners Hello World

C#
public class HelloWorld
{ 
  public static void Main()
  {
    System.Console.WriteLine("HELLO WORLD");
  }
}

2. Slightly improved version

C#
using System;

public class HelloWorld
{ 
  public static void Main()
  {
    Console.WriteLine("HELLO WORLD");
  }
} 

3. Command Line Arguments

C#
using System;

public class HelloWorld
{ 
  public static void Main(string[] args)
  {
    Console.WriteLine(args[0]);
  }
} 

4. From Constructor

C#
using System;
public class HelloWorld
{ 
  public HelloWorld()
  {
    Console.WriteLine("HELLO WORLD");
  }

  public static void Main() 
  {
    HelloWorld hw = new HelloWorld(); 
  }
}

5. More OO

C#
using System;
public class HelloWorld
{ 
  public void helloWorld()
  {
    Console.WriteLine("HELLO WORLD");
  }

  public static void Main() 
  {
    HelloWorld hw = new HelloWorld();
    hw.HelloWorld(); 
  }
}

6. From another class

C#
using System;
public class HelloWorld
{ 
  public static void Main()
  {
    HelloWorldHelperClass hwh = new HelloWorldHelperClass();
    hwh.writeHelloWorld(); 
  }
} 

public class HelloWorldHelperClass
{ 
  public void writeHelloWorld() 
  {
    Console.WriteLine("Hello World"); 
  }
} 

7. Inheritance

C#
abstract class HelloWorldBase
{
  public abstract void writeHelloWorld();
}
class HelloWorld : HelloWorldBase
{
  public override void writeHelloWorld() 
  { 
    Console.WriteLine("Hello World");
  }
}
class HelloWorldImp
{
  static void Main() {
    HelloWorldBase hwb = HelloWorld;
    HelloWorldBase.writeHelloWorld();
  }
}

8. Static Constructor

C#
using System;
public class HelloWorld
{ 
  private static string strHelloWorld;

  static HelloWorld()
  {
    strHelloWorld = "Hello World";
  }
  void writeHelloWorld()
  {
    Console.WriteLine(strHelloWorld);
  }

  public static void Main() 
  {
    HelloWorld hw = new HelloWorld();
    hw.writeHelloWorld(); 
  }
}

9. Exception Handling

C#
using System;

public class HelloWorld
{ 
  public static void Main(string[] args)
  {
    try
    {
      Console.WriteLine(args[0]);
    }
    catch(IndexOutOfRangeException e)
    {
      Console.WriteLine(e.ToString());
    }
  }
}

10. Creating a DLL and using it in an application

C#
using System;

namespace HelloLibrary
{
  public class HelloMessage
  {
    public string Message
    {
      get
      {
        return "Hello, World!!!";
      }
    }
  } 
}

//------

using System;
using HelloLibrary;

namespace HelloApplication
{
  class HelloApp
  {

    public static void Main(string[] args)
    {
      HelloMessage m = new HelloMessage();

    }
  }
}

11. Using Property

C#
using System;
public class HelloWorld
{ 
  public string strHelloWorld
  {
    get
    {
      return "Hello World";
    }
  }

  public static void Main() 
  {
    HelloWorld hw = new HelloWorld();
    Console.WriteLine(cs.strHelloWorld); 
  }
}

12. Using Delegates

C#
using System;
class HelloWorld
{
  static void writeHelloWorld() {
    Console.WriteLine("HelloWorld");
  }
  static void Main() {
    SimpleDelegate d = new SimpleDelegate(writeHelloWorld);
    d();
  }
}

13. Using Attributes

C#
#define DEBUGGING

using System;
using System.Diagnostics;

public class HelloWorld : Attribute
{
  [Conditional("DEBUGGING")]

  public void writeHelloWorld()
  {
    Console.WriteLine("Hello World");
  }

  public static void Main()
  {
    HelloWorld hw = new HelloWorld();

    hw.writeHelloWorld();
  }
}

14. Using Interfaces

C#
using System;

interface IHelloWorld
{
  void writeHelloWorld();
}

public class HelloWorld : IHelloWorld
{
  public void writeHelloWorld()
  {
    Console.WriteLine("Hello World");
  }

  public static void Main()
  {
    HelloWorld hw = new HelloWorld();

    hw.writeHelloWorld();
  }
}

15. Dynamic Hello World

C#
using System;
using System.Reflection;

namespace HelloWorldNS
{

  public class HelloWorld
  { 
    public string writeHelloWorld()
    {
      return "HelloWorld";
    }

    public static void Main(string[] args) 
    {
      Type hw = Type.GetType(args[0]);

      // Instantiating a class dynamically

      object[] nctorParams = new object[] {};
      object nobj = Activator.CreateInstance(hw, 
               nctorParams);

      // Invoking a method

      object[] nmthdParams = new object[] {};
      string strHelloWorld = (string) hw.InvokeMember(
              "writeHelloWorld", BindingFlags.Default | 
              BindingFlags.InvokeMethod, null, 
              nobj, nmthdParams);

      Console.WriteLine(strHelloWorld);
    }
  }
}

16. Unsafe Hello World

C#
using System;

public class HelloWorld
{ 
  unsafe public void writeHelloWorld(char[] chrArray)
  {
    fixed(char *parr = chrArray)
    {
      char *pch = parr;
      for(int i=0; i<chrArray.Length; i++)
        Console.Write(*(pch+i));
    }
  }

  public static void Main() 
  {
    HelloWorld hw = new HelloWorld();
    char[] chrHelloWorld = new char[] 
        {'H','e','l','l','o', ' ', 'W','o','r','l','d'};
    hw.writeHelloWorld(chrHelloWorld);
  }
}

17. Using InteropServices

C#
using System;
using System.Runtime.InteropServices;

class Class1
{
  [DllImport("kernel32")]
  private static extern int Beep(int dwFreq, int dwDuration);

  static void Main(string[] args)
  {
    Console.WriteLine("Hello World");
    Beep(1000, 2000);
  }
}

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


Written By
Architect
United States United States
Architect / Consultant on Content Management and Cloud Computing... Artist and Author by the weekends...

Comments and Discussions

 
GeneralStatic Constructor and Static Function Pin
Shabbazz3-Feb-04 0:25
professionalShabbazz3-Feb-04 0:25 
GeneralCool Beans! No Java Pun Intended... Pin
rsyoung0122-Jan-04 10:01
rsyoung0122-Jan-04 10:01 
GeneralStupid and Time Wasting article Pin
Member 33502221-Jan-04 22:38
Member 33502221-Jan-04 22:38 
GeneralRe: Stupid and Time Wasting article Pin
red_tomato14-May-04 6:58
red_tomato14-May-04 6:58 
GeneralRe: Stupid and Time Wasting article Pin
Butch.er2-Nov-04 0:57
Butch.er2-Nov-04 0:57 
Generalpretty good Pin
MyBlindy20-Jan-04 11:09
MyBlindy20-Jan-04 11:09 
GeneralNice article Pin
Per Søderlind12-Jan-04 20:20
sussPer Søderlind12-Jan-04 20:20 
QuestionDoesn't this remind you of an old joke? Pin
nsimeonov12-Jan-04 13:36
nsimeonov12-Jan-04 13:36 
AnswerRe: Doesn't this remind you of an old joke? Pin
Mike Kitchen13-Jan-04 22:03
Mike Kitchen13-Jan-04 22:03 
GeneralRe: Doesn't this remind you of an old joke? Pin
red_tomato14-May-04 6:54
red_tomato14-May-04 6:54 
GeneralRe: Doesn't this remind you of an old joke? Pin
Jason Lepack (LeppyR64)20-Nov-07 5:33
Jason Lepack (LeppyR64)20-Nov-07 5:33 
GeneralThis would be a great programming quiz! Pin
Marc Clifton12-Jan-04 12:57
mvaMarc Clifton12-Jan-04 12:57 
GeneralGreat Pin
hxxbin12-Jan-04 8:15
hxxbin12-Jan-04 8:15 
GeneralGreat Idea Pin
dhirschfeld12-Jan-04 7:14
dhirschfeld12-Jan-04 7:14 
GeneralInteresting Pin
dog_spawn12-Jan-04 3:07
dog_spawn12-Jan-04 3:07 
This seems like a quick way of looking up any forgotten C# syntax. I like it a lot. Did you come up with this? If yes, well done Smile | :)

I only have one critism: a beginner might have difficulty understand what the point of some of those examples are, because they all output "Hello world". We can see how it is a good reference, but they are left thinking, "why do it this way rather than another way?".

You could fix this by adding links to other articles at the bottom of each item. For example the DLL one could do with a link to an exlanation of what DLLs are in .NET and how they are used.
GeneralRe: Interesting Pin
Mike Ellison12-Jan-04 7:29
Mike Ellison12-Jan-04 7:29 

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