Call order of constructors for C + + aggregation relationship classes

, which represents an aggregation relationship

The following is a simple code to implement

1 #pragma once2class  Engine3{4public:  5    Engine (); 6     ~Engine (); 7 };

Engine.h

1#include <iostream>2#include"Engine.h"3 using namespacestd;4 5 Engine::engine ()6 {7cout <<"Call Constructor: Engine ()"<<Endl;8 }9 Tenengine::~Engine () One { Acout <<"Call destructor: ~engine ()"<<Endl; -}

Engine.cpp

1 #pragmaOnce2#include"Engine.h"3 4 classCar5 {6  Public:7 Car ();8~Car ();9 Private:Ten Engine M_ecar; One};

Car.h

1#include <iostream>2#include"Car.h"3 using namespacestd;4 5 Car::car ()6 {7cout <<"Call Constructor: Car ()"<<Endl;8 }9 Tencar::~Car () One { Acout <<"Call destructor: ~car ()"<<Endl; -}

Car.cpp

It can be seen that the order of the constructor call of the object is like we build the car, first build a good engine and other parts to assemble the car, the call of the destructor and the disassembly of the car, first open the outermost, and then the inside.

Call order of constructors for C + + aggregation relationship classes