104.virtual虚函数多态与异构数据结构

 #include "mainwindow.h"
 #include <QApplication>
 #include <list>
 #include <QPushButton>
 #include<QLabel>
 #include<QLineEdit>

 using namespace std;

 //异构数据结构,每个数组元素都是基类指针
 //异构链表,每一个结点都是基类的指针,指向了派生类
 //基类指针基于多态与虚函数调用派生类的方法

 class object
 {
 public:
     virtual void showit()
     {

     }
 };

 class mywindow:public object
 {
 public:
     MainWindow *p;

     mywindow()
     {
         p = new MainWindow;
     }

     void showit()
     {
         p->show();
      }
 };

 class mylabel:public object
 {
 public:
     QLabel *p;
     mylabel()
     {
         p=new QLabel;
     }
     void showit()
     {
         p->show();
     }
 };

 class myedit:public object
 {
 public:
     QLineEdit *p;
     myedit()
     {
         p=new QLineEdit;
     }
     void showit()
     {
         p->show();
     }
 };

 class mybutton:public object
 {
   public:
     QPushButton *p;
     mybutton()
     {
         p = new QPushButton;
     }

     void showit()
     {
         p->show();
     }
 };

 int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);

     list<object *>mylist;

     object *p = new mywindow;
     mylist.push_back(p);

     p = new mylabel;
     mylist.push_back(p);

     p = new mybutton;
     mylist.push_back(p);

     p = new mybutton;
     mylist.push_back(p);

     for(auto it:mylist)
     {
         (*it).showit();
     }
     return a.exec();
 }