[C++]对象的销毁机制

销毁时会按照从后向前的顺序销毁，也就是说，越在后面定义的对象会越早销毁。其中的原因就是函数是在栈中保存的，因此，先定义的对象先压栈，所以在退栈时就会后销毁。而如果参数有多个的话，大多数编译器是从右开始压栈的，也就是参数列表最右边的变量最先压栈，所以参数列表最右边的变量会在最后销毁。

代码如下：

#include<iostream>

using namespace std;

class Matter {
public:
    Matter(int id) : _identifier(id) 
        {cout << "Matter from " << _identifier << endl; }
    ~Matter()
        { cout << "Matter Bye from " << _identifier << endl; }

private:
    const int _identifier;
};

class World {
public:
    World(int id) : _identifier(id),_matter(id)
        {cout << "Hello from " << _identifier << endl; }
    ~World() { cout << "Bye from " << _identifier << endl; }

private:
    const int _identifier;
    Matter _matter;
};

World TheWorld(1);

int main() {
    World smallWorld(2);
    cout << "hello from main()\n";
    World oneMoreWorld(3);

    return 0;
}

输出结果

Matter from 1 
Hello from 1
Matter from 2 
Hello from 2 
Hello from main()
Matter from 3 
Hello from 3
Bye from 3
Matter Bye from 3
Bye from 2
Matter Bye from 2
Bye from 1
Matter Bye from 1