详解c# 多态

using System;
namespace PolymorphismApplication
{
 public class TestData 
 { 
 public int Add(int a, int b, int c) 
 { 
  return a + b + c; 
 } 
 public int Add(int a, int b) 
 { 
  return a + b; 
 } 
 } 
 class Program 
 { 
 static void Main(string[] args) 
 { 
  TestData dataClass = new TestData();
  int add1 = dataClass.Add(1, 2); 
  int add2 = dataClass.Add(1, 2, 3);

  Console.WriteLine("add1 :" + add1);
  Console.WriteLine("add2 :" + add2); 
 } 
 } 
}

using System;
namespace PolymorphismApplication
{
 class Printdata
 {
 void print(int i)
 {
  Console.WriteLine("输出整型: {0}", i );
 }

 void print(double f)
 {
  Console.WriteLine("输出浮点型: {0}" , f);
 }

 void print(string s)
 {
  Console.WriteLine("输出字符串: {0}", s);
 }
 static void Main(string[] args)
 {
  Printdata p = new Printdata();
  // 调用 print 来打印整数
  p.print(1);
  // 调用 print 来打印浮点数
  p.print(1.23);
  // 调用 print 来打印字符串
  p.print("Hello Runoob");
  Console.ReadKey();
 }
 }
}

using System;
namespace PolymorphismApplication
{
 abstract class Shape
 {
 abstract public int area();
 }
 class Rectangle: Shape
 {
 private int length;
 private int width;
 public Rectangle( int a=0, int b=0)
 {
  length = a;
  width = b;
 }
 public override int area ()
 {
  Console.WriteLine("Rectangle 类的面积：");
  return (width * length);
 }
 }

 class RectangleTester
 {
 static void Main(string[] args)
 {
  Rectangle r = new Rectangle(10, 7);
  double a = r.area();
  Console.WriteLine("面积： {0}",a);
  Console.ReadKey();
 }
 }
}

using System;
using System.Collections.Generic;

public class Shape
{
 public int X { get; private set; }
 public int Y { get; private set; }
 public int Height { get; set; }
 public int Width { get; set; }
 
 // 虚方法
 public virtual void Draw()
 {
 Console.WriteLine("执行基类的画图任务");
 }
}

class Circle : Shape
{
 public override void Draw()
 {
 Console.WriteLine("画一个圆形");
 base.Draw();
 }
}
class Rectangle : Shape
{
 public override void Draw()
 {
 Console.WriteLine("画一个长方形");
 base.Draw();
 }
}
class Triangle : Shape
{
 public override void Draw()
 {
 Console.WriteLine("画一个三角形");
 base.Draw();
 }
}

class Program
{
 static void Main(string[] args)
 {
 // 创建一个 List<Shape> 对象，并向该对象添加 Circle、Triangle 和 Rectangle
 var shapes = new List<Shape>
 {
  new Rectangle(),
  new Triangle(),
  new Circle()
 };

 // 使用 foreach 循环对该列表的派生类进行循环访问，并对其中的每个 Shape 对象调用 Draw 方法
 foreach (var shape in shapes)
 {
  shape.Draw();
 }

 Console.WriteLine("按下任意键退出。");
 Console.ReadKey();
 }

}

using System;
namespace PolymorphismApplication
{
 class Shape
 {
 protected int width, height;
 public Shape( int a=0, int b=0)
 {
  width = a;
  height = b;
 }
 public virtual int area()
 {
  Console.WriteLine("父类的面积：");
  return 0;
 }
 }
 class Rectangle: Shape
 {
 public Rectangle( int a=0, int b=0): base(a, b)
 {

 }
 public override int area ()
 {
  Console.WriteLine("Rectangle 类的面积：");
  return (width * height);
 }
 }
 class Triangle: Shape
 {
 public Triangle(int a = 0, int b = 0): base(a, b)
 {
 
 }
 public override int area()
 {
  Console.WriteLine("Triangle 类的面积：");
  return (width * height / 2);
 }
 }
 class Caller
 {
 public void CallArea(Shape sh)
 {
  int a;
  a = sh.area();
  Console.WriteLine("面积： {0}", a);
 }
 } 
 class Tester
 {
 
 static void Main(string[] args)
 {
  Caller c = new Caller();
  Rectangle r = new Rectangle(10, 7);
  Triangle t = new Triangle(10, 5);
  c.CallArea(r);
  c.CallArea(t);
  Console.ReadKey();
 }
 }
}