vc++中的类
#include<iostream.h>class A{
public:
a(int x=5){n=++x;}
void show(){cout<<"A:"<<n;}
int n; //A
};
class B:public A{
public:
B(int x=3){n=x*x;}
void show(){cout<<"B:"<<n;}
};
void main(void)
{B b;A a=b; //B
a.show();
}
解释下B行什么意思,并分析下运行过程和结果,谢谢