[C++]對象的銷毀機制

銷毀時會按照從后向前的順序銷毀，也就是說，越在后面定義的對象會越早銷毀。其中的原因就是函數是在棧中保存的，因此，先定義的對象先壓棧，所以在退棧時就會后銷毀。而如果參數有多個的話，大多數編譯器是從右開始壓棧的，也就是參數列表最右邊的變量最先壓棧，所以參數列表最右邊的變量會在最后銷毀。

代碼如下：

#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;
}

輸出結果

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