Why Virtual Functions: one interface, multiple methods : virtual function « Class « C++ Tutorial

Home
C++ Tutorial
1.Language Basics
2.Data Types
3.Operators statements
4.Array
5.Development
6.Exceptions
7.Function
8.Structure
9.Class
10.Operator Overloading
11.Pointer
12.File Stream
13.template
14.STL Introduction
15.string
16.vector
17.list
18.bitset
19.set multiset
20.valarray
21.queue stack
22.deque
23.map multimap
24.STL Algorithms Modifying sequence operations
25.STL Algorithms Non modifying sequence operations
26.STL Algorithms Binary search
27.STL Algorithms Sorting
28.STL Algorithms Merge
29.STL Algorithms Min Max
30.STL Algorithms Iterator
31.STL Algorithms Heap
32.STL Algorithms Helper
C / ANSI-C
C Tutorial
C++
Visual C++ .NET
C++ Tutorial » Class » virtual function 
9.28.9.Why Virtual Functions: one interface, multiple methods
#include <iostream>  
    using namespace std;       
  class Shape {  
  protected:  
    double x, y;  
  public:  
    void set_dim(double i, double j) {  
      x = i;  
      y = j;  
    }  
    virtual void show_area(void) {  
      cout << "No area computation defined ";  
      cout << "for this class.\n";  
    }  
  ;  
       
  class triangle : public Shape {  
    public:  
      void show_area(void) {  
        cout << "Triangle with height ";  
        cout << x << " and base " << y;  
        cout << " has an area of ";  
        cout << x * 0.5 * y << ".\n";  
      }  
  };  
       
  class square : public Shape {  
    public:  
      void show_area(void) {  
        cout << "Square with dimensions ";  
        cout << x << "x" << y;  
        cout << " has an area of ";  
        cout << x *  y << ".\n";  
      }  
  };  
       
  main(void)  
  {  
    Shape *p;  
       
    triangle t; 
    square s;  
       
    p = &t;  
    p->set_dim(10.05.0);  
    p->show_area();  
    p = &s;  
    p->set_dim(10.05.0);  
    p->show_area();  
       
    return 0;  
  }
9.28.virtual function
9.28.1.A virtual function
9.28.2.Access base class's virtual if derived class does not redefine it
9.28.3.Use virtual functions and polymorphism
9.28.4.A pure virtual function
9.28.5.Multiple virtual member functions called in turn
9.28.6.Class with only virtual methods
9.28.7.Use virtual function to calculate area for different shapes
9.28.8.Use Virtual Functions to change the method behaviour
9.28.9.Why Virtual Functions: one interface, multiple methods
9.28.10.Implementing pure virtual functions
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.