多态的问题请教

heavensword

#include <iostream.h>
using namespace std;

class Base
{

public:
        virtual Base * fn1(int x)
        {
                cout << "[fn1]In Base class " << endl;
                return this;
        }
        virtual Base * fn2()
        {
                cout << "[fn2]In Base class " << endl;
                return this;
        }

};
class SubClass : public Base  
{

public:
        virtual SubClass * fn1(float x)
        {
                cout << "[fn1]In Subclass class"<< endl;
                return this;
        }
        virtual SubClass * fn2()
        {
                cout << "[fn2]In Subclass class " << endl;
                return this;
        }

};


void test(Base & b)
{
        Base *bb;
        int i = 1;
        float f = 2.0;
        bb = b.fn1(i);
        bb = b.fn1(f);
        bb = b.fn2();
}

void main()
{
        Base bc;
        SubClass sc;
        cout << "Calling test(bc)"<<endl;
        test(bc);
        cout <<endl << "Calling test(sc)"<<endl;
        test(sc);
}

运行结果为:
Calling test(bc)
[fn1]In Base class
[fn1]In Base class
[fn2]In Base class

Calling test(sc)
[fn1]In Base class                      //为什么没有连接到 Subclass 中的fn1函数阿？
[fn1]In Base class
[fn2]In Subclass class                //为什么这个就连接到 Subclass 中的fn2函数阿？

哪个是 先期联编，哪个是迟后联编？
如何判断是否存在多态啊？

柳五随风

要搞清楚overload, oerlap,和override的区别.

heavensword

这几个单词只认识 重载
也查不到相关资料，晕倒

converse

http://www.cppblog.com/converse/archive/2006/03/24/4564.html