object slicing与虚函数
#include <iostream.h>
class CObject
{
public:
virtual void Serialize() { cout<<"CObject::Serialize()/n/n";}
};
class CDocument:public CObject
{
public:
void func()
{
cout<<"CDocument::func()"<<endl;
// Serialize();//这句代码主要是为了实现虚拟函数的调用
}
void Serialize() { cout<<"CDocument::Serialize()/n/n";}
};
class CMyDoc:public CDocument
{
public:
void Serialize() { cout<<"CMyDoc::Serialize()/n/n";}
};
void main()
{
CMyDoc mydoc;
CMyDoc *pmydoc=new CMyDoc;
cout<<"#1 testing"<<endl;
mydoc.func();
cout<<"#2 testing"<<endl;
((CDocument *)(&mydoc))->func();
cout<<"#3 testing"<<endl;
pmydoc->func();
cout<<"#4 testing"<<endl;
((CDocument)mydoc).func();
}
运行结果1：（注释掉函数func里Serialize()的的情况）
#1 testing
CDocument::func()
#2 testing
CDocument::func()
#3 testing
CDocument::func()
#4 testing
CDocument::func()
运行结果2：（没注释的情况）
#1 testing
CDocument::func()
CMyDoc::Serialize()
#2 testing
CDocument::func()
CMyDoc::Serialize()
#3 testing
CDocument::func()
CMyDoc::Serialize()
#4 testing
CDocument::func()
CDocument::Serialize()
经过所谓的data slicing,本例的mydoc真正变成了一个完完全全的CDocument对象