构造函数初始化列表执行顺序

构造函数初始化列表的顺序

证明了
1. 先初始化基类再初始化成员，在初始化列表初始类成员是类的，可以减少构造次数
2. 类成员是一个类是栈方式存储自动释放，指针类需手动释放

//类A
#include "A.h"
A::A(void)
{
    cout<< "create A"<<endl;
}
A::A(int x)
{
    cout<< "create A(x)"<<endl;
}
A::A(const A& a)
{
    cout<< "copy create A(a)"<<endl;
}
A::~A(void)
{
    cout<<"delete A"<<endl;
}

//类Bass
#include "Bass.h"
Bass::Bass(void)
{
    cout<< "create Bass"<<endl;
}
Bass::~Bass(void)
{
    cout<<"delete Bass"<<endl;
}

//类Sub 继承类Bass
class Sub:public Bass
{
public:
A b; 
A a;
A *pa;
    Sub(void);
    Sub(A &a);
    virtual~Sub(void);
};

#include "Sub.h"
Sub::Sub(void)
{
    cout<<"create Sub"<<endl;
}
Sub::Sub(A &a):a(1),b(a)
{
    cout<<"create Sub"<<endl;
}
Sub::~Sub(void)
{
    cout<<"delete Sub"<<endl;
}


//主函数类main
void fun()
{
A a;
    cout<<"==="<<endl;
    Sub b(a);
}

int main()
{
    fun();
return 0;
}

输出结果
create A
==

create Bass  
copy create A(a)
create A(x)
create Sub

delete Sub
delete A
delete A
delete Bass
delete A