关于'类的构造函数'和'该类的成员变量构造函数'调用的先后次序

#include <iostream>
#include <fstream>
using namespace std;

ofstream cout1("c://output.txt");
class OtherOb
{
public:
 OtherOb(){
  cout1<<"other ob"<<endl;
 }
 ~OtherOb(){
  cout1<<"~other ob"<<endl;
 }
};

class A
{
public:
 A() {
  cout1<<"A::A"<<endl;
 }
 virtual ~A(){
  cout1<<"~A::A"<<endl;
 }
};

class B:public A
{
public:
 B() {
  cout1<<"B::B"<<endl;
 }
 ~B(){
  cout1<<"~B::B"<<endl;
 }
 OtherOb a;
};

void main()
{
 A a;
 cout1<<"......"<<endl;
 B b;
 cout1<<"........"<<endl;

 A *c = new B;
 cout1<<"after delete c"<<endl;
 delete c;
 cout1<<"........"<<endl;
}

 

//////////////////////////////

A::A
......
A::A
other ob
B::B
........
A::A
other ob
B::B
after delete c
~B::B
~other ob
~A::A
........
~B::B
~other ob
~A::A
~A::A

 说明：把 OtherOb a; 改成A a;则输出结果在对应位置为A的构造或析构函数调用