C# Hello World写法入门:

1. 初学者

复制代码 代码如下:
public class HelloWorld
{
public static void Main()
{
System.Console.WriteLine("HELLO WORLD");
}
}

2. 改进的HELLO WORLD

复制代码 代码如下:
using System;

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

3. 命令行形式

复制代码 代码如下:
using System;

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

4. 构造函数

复制代码 代码如下:
using System;

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

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

C# Hello World写法进阶:

5. 面向对象

复制代码 代码如下:
using System;

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

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

6. 从其他类

复制代码 代码如下:
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. 继承

复制代码 代码如下:
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. 静态构造函数

复制代码 代码如下:
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. 异常处理

复制代码 代码如下:
using System;

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

10. 名字空间

复制代码 代码如下:
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. 属性

复制代码 代码如下:
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. 代理

复制代码 代码如下:
using System;
class HelloWorld
{
static void writeHelloWorld()
{
Console.WriteLine("HelloWorld");
}
static void Main()
{
SimpleDelegate d = new SimpleDelegate(writeHelloWorld);
d();
}
}

13. 使用属性

复制代码 代码如下:
#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. 接口

复制代码 代码如下:
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();
}
}

C# Hello World的特别写法:

15. 动态Hello World

复制代码 代码如下:
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);//, 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. 不安全代码Hello World

复制代码 代码如下:
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. 使用InteropServices

复制代码 代码如下:
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);
}
}