C++构造函数和析构函数的调用顺序

1、 构造函数的调用顺序

基类构造函数、对象成员构造函数、派生类本身的构造函数

2、析构函数 的调用顺序

派生类本身的析构函数、对象成员析构函数、基类析构函数（与构造顺序正好相反）

3、特例

局部对象，在退出程序块时析构

静态对象，在定义所在文件结束时析构

全局对象，在程序结束时析构

继承对象，先析构派生类，再析构父类

对象成员，先析构类对象，再析构对象成员

4、例子

#include <iostream>

using namespace std;

class Base1

{

public:

    Base1(void){cnt++;cout<<"Base1::constructor("<<cnt<<")"<<endl;}

    ~Base1(void){cnt--;cout<<"Base1::deconstructor("<<cnt + <<")"<<endl;}

private:

    static int cnt;

};

int Base1::cnt = ;

class Base2

{

public:

    Base2(int m){num = m; cout<<"Base2::constructor("<<num<<")"<<endl;}

    ~Base2(void){cout<<"Base2::deconstructor("<<num<<")"<<endl;}

private:

    int num;

};

class Example

{

public:

    Example(int n){num = n; cout<<"Example::constructor("<<num<<")"<<endl;}

    ~Example(void){cout<<"Example::deconstructor("<<num<<")"<<endl;}

private:

    int num;

};

class Derived:public Base1, public Base2

{

public:

    Derived(int m, int n):Base2(m),ex(n){cnt++;cout<<"Derived::constructor("<<cnt<<")"<<endl;}

    ~Derived(void){cnt--;cout<<"Derived::deconstructor("<<cnt+<<")"<<endl;}

private:

    Example ex;

    static Example stex;    //Example::constructor(1) //不能输出

    static int cnt;

};

int Derived::cnt = ;

Derived ge_a(,); // Base1::constructor(1)

                   // Base2::constructor(1)

                   // Example::constructor(2)

                   // Derived::constructor(1)

static Derived gs_b(,);   // Base1::constructor(2)

                            // Base2::constructor(3)

                            // Example::constructor(4)

                            // Derived::constructor(2)

int main(void)

{

    cout << "---------start---------" << endl;

    Derived d(,); // Base1::constructor(3)

                    // Base2::constructor(5)

                    // Example::constructor(6)

                    // Derived::constructor(3)

    Derived e(,); // Base1::constructor(4)

                    // Base2::constructor(7)

                    // Example::constructor(8)

                    // Derived::constructor(4)

    cout << "----------end----------" << endl;

    //Derived e(7,8) 析构

            // Derived::deconstructor(4)

            // Example::deconstructor(8)

            // Base2::deconstructor(7)

            // Base1::deconstructor(4)

    //Derived d(5,6) 析构

            // Derived::deconstructor(3)

            // Example::deconstructor(6)

            // Base2::deconstructor(5)

            // Base1::deconstructor(3)

    return ;

}

//static Derived gs_b(3,4) 析构

        // Derived::deconstructor(2)

        // Example::deconstructor(4)

        // Base2::deconstructor(3)

        // Base1::deconstructor(2)

//Derived ge_a(1,2) 析构

        // Derived::deconstructor(1)

        // Example::deconstructor(2)

        // Base2::deconstructor(1)

        // Base1::deconstructor(1)

//static Example stex 析构

        //Example::deconstructor(1) //不能输出 

#include <iostream>

using namespace std;

class A

{

public:

     A(){cout<<"A::constructor"<<endl;};

     ~A(){cout<<"A::deconstructor"<<endl;};

};

class B

{

public:

     B(){cout<<"B::constructor"<<endl;};

     ~B(){cout<<"B::deconstructor"<<endl;};

};

class C : public A

{

public:

     C(){cout<<"C::constructor"<<endl;};

     ~C(){cout<<"C::deconstructor"<<endl;};

private:

//    static B b;

     B b;

};

class D : public C

{

public:

     D(){cout<<"D::constructor"<<endl;};

     ~D(){cout<<"D::deconstructor"<<endl;};

};

int main(void)

{

    C* pd = new D();

    delete pd;

    return ;

}

/* Output

----->B b

A::constructor

B::constructor

C::constructor

D::constructor

C::deconstructor

B::deconstructor

A::deconstructor

----->static B b

A::constructor

C::constructor

D::constructor

C::deconstructor

A::deconstructor

 */