使用C#编写17种Hello World程序(初学者C#测试石)

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使用C#编写17种Hello World程序(初学者C#测试石)

1. A Beginners Hello World   初学者

代码 public?class?HelloWorld
{?
??public?static?void?Main()
??{
????System.Console.WriteLine("HELLO?WORLD");
??}
}
2. Slightly improved version???略有提高 

代码 using?System;??（就这？会用命名空间？）
public?class?HelloWorld
{?
??public?static?void?Main()
??{
????Console.WriteLine("HELLO?WORLD");
??}
}? 3. Command Line Arguments   命令行参数

 

代码 using?System;
public?class?HelloWorld
{?
??public?static?void?Main(string[]?args)???//会传参数了
??{
????Console.WriteLine(args[0]);
??}
}? 4. From Constructor    构造函数

 

代码 using?System;
public?class?HelloWorld
{?
??public?HelloWorld()
??{
????Console.WriteLine("HELLO?WORLD");
??}
??public?static?void?Main()?
??{
????HelloWorld?hw?=?new?HelloWorld();??//会用类了？构造？
??}
} 5. More OO   

 

代码 using?System;
public?class?HelloWorld
{?
??public?void?helloWorld()
??{
????Console.WriteLine("HELLO?WORLD");
??}
??public?static?void?Main()?
??{
????HelloWorld?hw?=?new?HelloWorld();
????hw.HelloWorld();???//更进一步的面向对象？会用方法了？
??}
} 6. From another class  调用另一个类

 

代码 using?System;
public?class?HelloWorld
{?
??public?static?void?Main()
??{
????HelloWorldHelperClass?hwh?=?new?HelloWorldHelperClass();???//类里调用其它类？
????hwh.writeHelloWorld();?
??}
}
public?class?HelloWorldHelperClass
{?
??public?void?writeHelloWorld()?
??{
????Console.WriteLine("Hello?World");?
??}
}? 7. Inheritance  继承

 

代码 abstract?class?HelloWorldBase??//抽象类
{
????public?abstract?void?writeHelloWorld();
}
class?HelloWorld?:?HelloWorldBase??//继承----不得不严肃起来了，能抽象的已经可以做系统架构设计了！
{
????public?override?void?writeHelloWorld()
????{
????????Console.WriteLine("Hello?World");
????????Console.ReadLine();
????}
}
class?HelloWorldImp
{
????static?void?Main()
????{
????????HelloWorldBase?hwb?=?new?HelloWorld();
????????hwb.writeHelloWorld();
????}
}

 

8. Static Constructor 静态构造函数

代码 using?System;
public?class?HelloWorld
{?
??private?static?string?strHelloWorld;
??static?HelloWorld()????//静态构造
??{
????strHelloWorld?=?"Hello?World";
??}
??void?writeHelloWorld()
??{
????Console.WriteLine(strHelloWorld);????}
??public?static?void?Main()?
??{
????HelloWorld?hw?=?new?HelloWorld();???//需要吗？
????hw.writeHelloWorld();???//平常我会觉得很可笑----居然写得这么啰嗦

??}
} 9. Exception Handling  异常处理

 

代码 using?System;
public?class?HelloWorld
{?
??public?static?void?Main(string[]?args)
??{
????try
????{
??????Console.WriteLine(args[0]);
????}
????catch(IndexOutOfRangeException?e)???//会用异常处理了,但如何更好回收资源呢？异常接下来应该是资源回收啊？我以前也犯这种毛病，GC应该怎么更好使用，我到现在还不是很纯熟
????{
??????Console.WriteLine(e.ToString());
????}
??}

10. Creating a DLL and using it in an application   做组件吗？

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

 

//------

代码 using?System;
using?HelloLibrary;
namespace?HelloApplication
{
??class?HelloApp
??{
????public?static?void?Main(string[]?args)
????{
??????HelloMessage?m?=?new?HelloMessage();
????}
??}
}

 

11. Using Property   实用属性

代码 using?System;
public?class?HelloWorld
{
????public?string?strHelloWorld
????{
????????get???//会用属性了
????????{
????????????return?"Hello?World";
????????}
????}
????public?static?void?Main()
????{
????????HelloWorld?hw?=?new?HelloWorld();
????????Console.WriteLine(hw.strHelloWorld);
????}
}

12. Using Delegates    //委托！

代码 using?System;

class?HelloWorld
{
????delegate?void?SimpleDelegate();//定义委托

????static?void?writeHelloWorld()
????{
????????Console.WriteLine("HelloWorld");
????}

????static?void?Main()
????{
????????SimpleDelegate?d?=?new?SimpleDelegate(writeHelloWorld);??//委托？！？！
????????d();???//语法的确这么写，但含义无法理解;因为实在体会不出好处来
????}
} 13. Using Attributes    //我不会！补习去！

 

代码 #define?DEBUGGING
using?System;
using?System.Diagnostics;
public?class?HelloWorld?:?Attribute
{
????[Conditional("DEBUGGING")]
????public?void?writeHelloWorld()
????{
????????Console.WriteLine("Hello?World");
????????Console.ReadLine();
????}
????public?static?void?Main()
????{
????????HelloWorld?hw?=?new?HelloWorld();
????????hw.writeHelloWorld();
????}
} 14. Using Interfaces???//接口

 

代码 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  //Again

 

代码 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   //Unsafe

 

代码 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

代码 using?System;
using?System.Runtime.InteropServices;
class?Class1
{??//COM?,??API接口??我以前就这么低俗地理解.????其实工具会帮你生成
????[DllImport("kernel32")]
????private?static?extern?int?Beep(int?dwFreq,?int?dwDuration);
????static?void?Main(string[]?args)
????{
????????Console.WriteLine("Hello?World");
????????Beep(1000,?2000);
????}
}?

原文地址:http://www.cnblogs.com/babyblue/archive/2004/03/11/2852.html

posted on 2009-11-27 11:32 peter Chen 阅读(...) 评论(...) 编辑 收藏

转载于:https://www.cnblogs.com/peter120123/archive/2009/11/27/1611852.html

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