c 构造函数和析构函数的调用顺序-ag真人游戏

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 
using namespace std;
class base1
{
public:
    base1(void){cnt  ;cout<<"base1::constructor("<")"<<endl;}
    ~base1(void){cnt--;cout<<"base1::deconstructor("<1<<")"<<endl;}
private:
    static int cnt;
};
int base1::cnt = 0;
class base2
{
public:
    base2(int m){num = m; cout<<"base2::constructor("<")"<<endl;}
    ~base2(void){cout<<"base2::deconstructor("<")"<<endl;}
private:
    int num;
};
class example
{
public:
    example(int n){num = n; cout<<"example::constructor("<")"<<endl;}
    ~example(void){cout<<"example::deconstructor("<")"<<endl;}
private:
    int num;
};
class derived:public base1, public base2
{
public:
    derived(int m, int n):base2(m),ex(n){cnt  ;cout<<"derived::constructor("<")"<<endl;}
    ~derived(void){cnt--;cout<<"derived::deconstructor("<1<<")"<<endl;}
private:
    example ex;
    static example stex;    //example::constructor(1) //不能输出
    static int cnt;
};
int derived::cnt = 0;
derived ge_a(1,2); // base1::constructor(1)
                   // base2::constructor(1)
                   // example::constructor(2)
                   // derived::constructor(1)
static derived gs_b(3,4);   // base1::constructor(2)
                            // base2::constructor(3)
                            // example::constructor(4)
                            // derived::constructor(2)
int main(void)
{
    cout << "---------start---------" << endl;
    derived d(5,6); // base1::constructor(3)
                    // base2::constructor(5)
                    // example::constructor(6)
                    // derived::constructor(3)
    derived e(7,8); // 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 0;
}
//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 
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 0;
}
/* 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
 */