Question

求教c++问题,解释一下，谢谢

#include<iostream.h>
class A
{ int x;
public:
A(int a):x(a) {cout<<"constructing A";}
};
class B:public A
{
public:
B(){ cout<<"constructing B";}
};
void main()
{
B b;
}

Answer 1

A(int a):x(a) {cout<<"constructing A";}
就是A(int a)
{
x=a;
cout<<"constructing A";
}
然后就是继承中，派生类和基类的构造函数调用顺序的问题了，先调用基类的构造函数，执行cout<<"constructing A; 然后调用派生类的构造函数，执行cout<<"constructing B;。这就是你想要的答案吧。