使用C#编写不同的“Hello World”程序
1. A Beginners Hello Worldpublic class HelloWorld
{
public static void Main()
{
System.Console.WriteLine("HELLO WORLD");
}
}
2. Slightly improved versionusing System;
public class HelloWorld
{
public static void Main()
{
Console.WriteLine("HELLO WORLD");
}
}
3. Command Line Argumentsusing System;
public class HelloWorld
{
public static void Main(string[] args)
{
Console.WriteLine(args[0]);
}
}
4. From Constructorusing System;
public class HelloWorld
{
public HelloWorld()
{
Console.WriteLine("HELLO WORLD");
}
public static void Main()
{
HelloWorld hw = new HelloWorld();
}
}
5. More OOusing System;
public class HelloWorld
{
public void helloWorld()
{
Console.WriteLine("HELLO WORLD");
}
public static void Main()
{
HelloWorld hw = new HelloWorld();
hw.HelloWorld();
}
}
6. From another classusing 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. Inheritanceabstract 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 Constructorusing 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 Handlingusing 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 applicationusing 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 Propertyusing 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 Delegatesusing System;
class HelloWorld
{
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 Interfacesusing 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 Worldusing 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 Worldusing 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 InteropServicesusing 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);
}
}
