继承构造函数的执行顺序

转自：http://blog.csdn.net/daheiantian/article/details/6438782

Code:

#include <iostream>
using namespace std;

class A {
public:
A() {
cout<<"int A::A()"<<endl;
}
A(A &a) {
cout<<"int A::A(A &a)"<<endl;
}
A& operator=(A& a) {
cout<<"int A::operator=(A &a)"<<endl;
return a;
}
virtual ~A() {
cout<<"int A::~A()"<<endl;
}
};

class M :public A {
public:
M() {
cout<<"int M::M()"<<endl;
}
M(M &a) {
cout<<"int M::M(M &a)"<<endl;
}
M& operator=(M& m) {
cout<<"int M::operator=(M &a)"<<endl;
return m;
}
virtual ~M() {
cout<<"int M::~M()"<<endl;
}
};

class B:virtual public M {
public:
B() {
cout<<"int B::B()"<<endl;
}
B(B &a) {
cout<<"int B::B(B &a)"<<endl;
}
B& operator=(B& b) {
cout<<"int B::operator=(B &a)"<<endl;
return b;
}
virtual ~B() {
cout<<"int B::~B()"<<endl;
}

};

class N :public A {
public:
N() {
cout<<"int N::N()"<<endl;
}
N(N &a) {
cout<<"int N::N(N &a)"<<endl;
}
N& operator=(N& n) {
cout<<"int N::operator=(N &a)"<<endl;
return n;
}
virtual ~N() {
cout<<"int N::~N()"<<endl;
}
};
class C:virtual public N {
public:
C() {
cout<<"int C::C()"<<endl;
}
C(C &a) {
cout<<"int C::C(C &a)"<<endl;
}
C& operator=(C& c) {
cout<<"int C::operator=(C &a)"<<endl;
return c;
}
virtual ~C() {
cout<<"int C::~C()"<<endl;
}
};
class E:virtual public M{
public:
E() {
cout<<"int E::E()"<<endl;
}
E(E &a) {
cout<<"int E::E(E &a)"<<endl;
}
E& operator=(E& e) {
cout<<"int E::operator=(E &a)"<<endl;
return e;
}
virtual ~E() {
cout<<"int E::~E()"<<endl;
}
};
class D:public B, public C, public E {
public:
D() {
cout<<"int D::D()"<<endl;
}
D(D &a) {
cout<<"int D::D(D &a)"<<endl;
}
D& operator=(D& d) {
cout<<"int D::operator=(D &a)"<<endl;
return d;
}
virtual ~D() {
cout<<"int D::~D()"<<endl;
}
};

int main(int argc, char **argv) {
cout<<"-------构造函数-------"<<endl;
D d;
cout<<"-------复制构造函数-------"<<endl;
D d1(d);
cout<<"-------赋值操作符-------"<<endl;
d = d1;
cout<<"-------析构函数-------"<<endl;

return 0;
}

Result：

-------构造函数-------
int A::A()
int M::M()//构造虚基类M时，要先构造其父类A
int A::A()
int N::N()//和M一样，构造虚基类N时，也要先构造其父类A
int B::B()//构造完虚基类，开始构造直接父类，按照声明顺序为B、C、E
int C::C()
int E::E()
int D::D()//最后构造自己
-------复制构造函数-------
int A::A()
int M::M()
int A::A()
int N::N()
int B::B()
int C::C()
int E::E()
int D::D(D &a)//因为D中定义了复制构造函数，并且没有显式调用父类的构造函数，所以所有的“虚基类”和“直接父类”都调用默认构造函数
-------赋值操作符-------
int D::operator=(D &a) //因为显式调用了赋值操作符，那么就只调用自己的代码，不会隐式调用其它的函数
-------析构函数-------
int D::~D()
int E::~E()
int C::~C()
int B::~B()
int N::~N()
int A::~A()
int M::~M()
int A::~A()//因为main函数中定义了两个D对象，所以main函数结束时要进行析构两个D对象。析构的顺序与 构造函数相反。
int D::~D()
int E::~E()
int C::~C()
int B::~B()
int N::~N()
int A::~A()
int M::~M()
int A::~A()

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