Hello World In different Styles

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 C# language and .NET framework.

1. A Beginner Hello World

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

2. Slightly improved version

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

3. Command Line Arguments

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

4. From Constructor

using System;
public class HelloWorld
{
    public HelloWorld()
    {
        Console.WriteLine("HELLO WORLD");
    }
    public static void Main()
    {
        HelloWorld hw = new HelloWorld();
    }
}

5. More OO

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

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

using System;
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 = new HelloWorld();
        hwb.WriteHelloWorld();
    }
}

8. Static Constructor

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

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

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();
            // Additional code for using the HelloMessage object can be added here if needed
        }
    }
}

11. Using Property

using System;
public class HelloWorld
{
    public string StrHelloWorld
    {
        get
        {
            return "Hello World";
        }
    }
    public static void Main()
    {
        HelloWorld hw = new HelloWorld();
        Console.WriteLine(hw.StrHelloWorld);
    }
}

12. Using Delegates

using System;
public class HelloWorld
{
    delegate void SimpleDelegate();
    static void WriteHelloWorld()
    {
        Console.WriteLine("HelloWorld");
    }
    static void Main()
    {
        SimpleDelegate d = new SimpleDelegate(WriteHelloWorld);
        d();
    }
}

13. Using Attributes

#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

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

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

using System;
public class HelloWorld
{
    unsafe public void WriteHelloWorld(char[] charArray)
    {
        fixed (char* ptr = charArray)
        {
            char* pch = ptr;
            for (int i = 0; i < charArray.Length; i++)
            {
                Console.Write(*(pch + i));
            }
        }
    }
    public static void Main()
    {
        HelloWorld hw = new HelloWorld();
        char[] charHelloWorld = { 'H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd' };
        hw.WriteHelloWorld(charHelloWorld);
    }
}

17. Using InteropServices

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);
    }
}

2 Comments

Join the conversation! Your thoughts help the community grow.

Kumaresh Rajalingam10y ago
Good Thinking
muthu kumar16y agoedited
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(); } } How can you create object(instantiation) for abstract classes. This artcile has been published in 2004 but no comments are available.Hasnt anybody viewed this article(I'm Puzzled). Explanation of different ways was indeed a good task.