chap11.lst

Csharp2完全参考手册源代码 详细的说明可以在书里看到 该书是08年刚出炉很新鲜

listing 1
// A simple class hierarchy. 
 
using System; 
 
// A class for two-dimensional objects. 
class TwoDShape { 
  public double width; 
  public double height; 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// Triangle is derived from TwoDShape. 
class Triangle : TwoDShape { 
  public string style; // style of triangle 
   
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class Shapes { 
  public static void Main() { 
    Triangle t1 = new Triangle(); 
    Triangle t2 = new Triangle(); 
 
    t1.width = 4.0; 
    t1.height = 4.0; 
    t1.style = "isosceles"; 
 
    t2.width = 8.0; 
    t2.height = 12.0; 
    t2.style = "right"; 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

listing 2
// Private members are not inherited.  
 
// This example will not compile. 
using System; 
 
// A class for two-dimensional objects. 
class TwoDShape { 
  double width;  // now private 
  double height; // now private 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// Triangle is derived from TwoDShape. 
class Triangle : TwoDShape { 
  public string style; // style of triangle 
   
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; // Error, can't access private member 
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
}

listing 3
// Use properties to set and get private members. 
 
using System; 
 
// A class for two-dimensional objects. 
class TwoDShape { 
  double pri_width;  // now private 
  double pri_height; // now private  
 
  // Properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// A derived class of TwoDShape for triangles. 
class Triangle : TwoDShape { 
  public string style; // style of triangle 
   
  // Return area of triangle. 
  public double area() { 
    return width * height / 2;  
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class Shapes2 { 
  public static void Main() { 
    Triangle t1 = new Triangle(); 
    Triangle t2 = new Triangle(); 
 
    t1.width = 4.0; 
    t1.height = 4.0; 
    t1.style = "isosceles"; 
 
    t2.width = 8.0; 
    t2.height = 12.0; 
    t2.style = "right"; 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

listing 4
// Demonstrate protected. 
 
using System; 
 
class B { 
  protected int i, j; // private to B, but accessible by D 
 
  public void set(int a, int b) { 
    i = a; 
    j = b; 
  } 
 
  public void show() { 
    Console.WriteLine(i + " " + j); 
 } 
} 
 
class D : B { 
  int k; // private 
 
  // D can access B's i and j 
  public void setk() { 
     k = i * j; 
  } 
 
  public void showk() { 
    Console.WriteLine(k); 
  } 
} 
 
class ProtectedDemo { 
  public static void Main() { 
    D ob = new D(); 
 
    ob.set(2, 3); // OK, known to D 
    ob.show();    // OK, known to D 
 
    ob.setk();  // OK, part of D 
    ob.showk(); // OK, part of D 
  } 
}

listing 5
// Add a constructor to Triangle. 
 
using System; 
 
// A class for two-dimensional objects. 
class TwoDShape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  // properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// A derived class of TwoDShape for triangles. 
class Triangle : TwoDShape { 
  string style; // private 
   
  // Constructor 
  public Triangle(string s, double w, double h) { 
    width = w;  // init the base class 
    height = h; // init the base class 
 
    style = s;  // init the derived class 
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2;  
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class Shapes3 { 
  public static void Main() { 
    Triangle t1 = new Triangle("isosceles", 4.0, 4.0); 
    Triangle t2 = new Triangle("right", 8.0, 12.0); 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

listing 6
// Add constructors to TwoDShape. 
 
using System; 
 
// A class for two-dimensional objects. 
class TwoDShape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  // Constructor for TwoDShape. 
  public TwoDShape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  // properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
 // A derived class of TwoDShape for triangles. 
class Triangle : TwoDShape { 
  string style; // private 
   
  // Call the base class constructor. 
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class Shapes4 { 
  public static void Main() { 
    Triangle t1 = new Triangle("isosceles", 4.0, 4.0); 
    Triangle t2 = new Triangle("right", 8.0, 12.0); 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

listing 7
// Add more constructors to TwoDShape. 
 
using System; 
 
class TwoDShape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  // Default constructor. 
  public TwoDShape() { 
    width = height = 0.0; 
  } 
 
  // Constructor for TwoDShape. 
  public TwoDShape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  // Construct object with equal width and height. 
  public TwoDShape(double x) { 
    width = height = x; 
  } 
 
  // Properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// A derived class of TwoDShape for triangles. 
class Triangle : TwoDShape { 
  string style; // private 
   
  /* A default constructor. This automatically invokes 
     the default constructor of TwoDShape. */ 
  public Triangle() { 
    style = "null"; 
  } 
 
  // Constructor that takes three arguments. 
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Construct an isosceles triangle. 
  public Triangle(double x) : base(x) { 
    style = "isosceles";  
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
class Shapes5 { 
  public static void Main() { 
    Triangle t1 = new Triangle(); 
    Triangle t2 = new Triangle("right", 8.0, 12.0); 
    Triangle t3 = new Triangle(4.0); 
 
    t1 = t2; 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    Console.WriteLine("Area is " + t2.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t3: "); 
    t3.showStyle(); 
    t3.showDim(); 
    Console.WriteLine("Area is " + t3.area()); 
 
    Console.WriteLine(); 
  } 
}

listing 8
// An example of inheritance-related name hiding. 
 
using System; 
 
class A { 
  public int i = 0; 
} 
 
// Create a derived class. 
class B : A { 
  new int i; // this i hides the i in A 
 
  public B(int b) { 
    i = b; // i in B 
  } 
 
  public void show() { 
    Console.WriteLine("i in derived class: " + i); 
  } 
} 
 
class NameHiding { 
  public static void Main() { 
    B ob = new B(2); 
 
    ob.show(); 
  } 
}

listing 9
// Using base to overcome name hiding. 
 
using System; 
 
class A { 
  public int i = 0; 
} 
 
// Create a derived class. 
class B : A { 
  new int i; // this i hides the i in A 
 
  public B(int a, int b) { 
    base.i = a; // this uncovers the i in A 
    i = b; // i in B 
  } 
 
  public void show() { 
    // this displays the i in A. 
    Console.WriteLine("i in base class: " + base.i); 
 
    // this displays the i in B 
    Console.WriteLine("i in derived class: " + i); 
  } 
} 
 
class UncoverName { 
  public static void Main() { 
    B ob = new B(1, 2); 
 
    ob.show(); 
  } 
}

listing 10
// Call a hidden method. 
 
using System; 
 
class A { 
  public int i = 0; 
 
  // show() in A 
  public void show() { 
    Console.WriteLine("i in base class: " + i); 
  } 
} 
 
// Create a derived class. 
class B : A { 
  new int i; // this i hides the i in A 
 
  public B(int a, int b) { 
    base.i = a; // this uncovers the i in A 
    i = b; // i in B 
  } 

  // This hides show() in A. Notice the use of new. 
  new public void show() { 
    base.show(); // this calls show() in A 
 
    // this displays the i in B 
    Console.WriteLine("i in derived class: " + i); 
  } 
} 
 
class UncoverName { 
  public static void Main() { 
    B ob = new B(1, 2); 
 
    ob.show(); 
  } 
}

listing 11
// A multilevel hierarchy. 
 
using System; 
 
class TwoDShape { 
  double pri_width;  // private 
  double pri_height; // private  
 
  // Default constructor. 
  public TwoDShape() { 
    width = height = 0.0; 
  } 
 
  // Constructor for TwoDShape. 
  public TwoDShape(double w, double h) { 
    width = w; 
    height = h; 
  } 
 
  // Construct object with equal width and height. 
  public TwoDShape(double x) { 
    width = height = x; 
  } 
 
  // Properties for width and height. 
  public double width { 
     get { return pri_width; } 
     set { pri_width = value; } 
  } 
 
  public double height { 
     get { return pri_height; } 
     set { pri_height = value; } 
  } 
 
  public void showDim() { 
    Console.WriteLine("Width and height are " + 
                       width + " and " + height); 
  } 
} 
 
// A derived class of TwoDShape for triangles. 
class Triangle : TwoDShape { 
  string style; // private 
   
  /* A default constructor. This invokes the default 
     constructor of TwoDShape. */ 
  public Triangle() { 
    style = "null"; 
  } 
 
  // Constructor 
  public Triangle(string s, double w, double h) : base(w, h) { 
    style = s;  
  } 
 
  // Construct an isosceles triangle. 
  public Triangle(double x) : base(x) { 
    style = "isosceles";  
  } 
 
  // Return area of triangle. 
  public double area() { 
    return width * height / 2; 
  } 
 
  // Display a triangle's style. 
  public void showStyle() { 
    Console.WriteLine("Triangle is " + style); 
  } 
} 
 
// Extend Triangle. 
class ColorTriangle : Triangle { 
  string color; 
 
  public ColorTriangle(string c, string s, 
                       double w, double h) : base(s, w, h) { 
    color = c; 
  } 
 
  // Display the color. 
  public void showColor() { 
    Console.WriteLine("Color is " + color); 
  } 
} 
 
class Shapes6 { 
  public static void Main() { 
    ColorTriangle t1 =  
         new ColorTriangle("Blue", "right", 8.0, 12.0); 
    ColorTriangle t2 =  
         new ColorTriangle("Red", "isosceles", 2.0, 2.0); 
 
    Console.WriteLine("Info for t1: "); 
    t1.showStyle(); 
    t1.showDim(); 
    t1.showColor(); 
    Console.WriteLine("Area is " + t1.area()); 
 
    Console.WriteLine(); 
 
    Console.WriteLine("Info for t2: "); 
    t2.showStyle(); 
    t2.showDim(); 
    t2.showColor(); 
    Console.WriteLine("Area is " + t2.area()); 
  } 
}

listing 12
// Demonstrate when constructors are called. 
 
using System; 
 
// Create a base class. 
class A { 
  public A() {  
    Console.WriteLine("Constructing A."); 
  } 
} 
 
// Create a class derived from A. 
class B : A { 
  public B() { 
    Console.WriteLine("Constructing B."); 
  } 
} 
 
// Create a class derived from B. 
class C : B { 
  public C() { 
    Console.WriteLine("Constructing C."); 
  } 
} 
 
class OrderOfConstruction { 
  public static void Main() { 
    C c = new C(); 
  } 
}

listing 13