带你粗略了解C++中的深浅拷贝

#ifndef COPY__CAR_H_
#define COPY__CAR_H_
#include "Engine.h"
#include <string>
using namespace std;
class Car {
 public:
  // 构造函数
  Car();
  Car(string brand, int version);
  ~Car();
  // 添加或者修改一个引擎
  void setEngine(string engine_brand, int engine_version);
  // 对汽车信息进行描述
  string description() const;
 private:
  string brand; // 品牌
  int version; // 型号
  Engine *engine; // 引擎
};
#endif //COPY__CAR_H_

#include "Car.h"
#include <sstream>
Car::Car() {
  this->brand = "无";
  this->version = 0;
  this->engine = nullptr;
}
Car::Car(string brand, int version) {
  engine = nullptr;
  this->brand = brand;
  this->version = version;
}
Car::~Car() {
}
void Car::setEngine(string engine_brand, int engine_version) {
  if (engine) {
    delete engine;
  }
  engine = new Engine(engine_brand, engine_version);
}
string Car::description() const {
  stringstream result;
  result << "品牌:" << brand << " 版本:" << version << engine->description();
  return result.str();
}

#ifndef COPY__ENGINE_H_
#define COPY__ENGINE_H_
#include <string>
using namespace std;
class Engine {
 public:
  Engine();
  Engine(string brand, int version);
  ~Engine();
  string description() const;
 private:
  string brand;
  int version;
};
#endif //COPY__ENGINE_H_

#include "Engine.h"
#include <sstream>
Engine::Engine() {
  this->brand = "无";
  this->version = 0;
}
Engine::Engine(string brand, int version) {
  this->brand = brand;
  this->version = version;
}
Engine::~Engine() {
}
string Engine::description() const {
  stringstream result;
  result << " 发动机品牌:" << brand << " 发动机版本:" << version;
  return result.str();
}

#include "Car.h"
#include <iOStream>
using namespace std;
int main() {
  // 创建car_1对象
  Car car_1("宝马", 1);
  // 为car_1对象添加一个引擎
  car_1.setEngine("宝马", 1);
  // 创建car_2对象, 并且拷贝自car_1
  Car car_2(car_1);
  // 输出修改引擎前的两个对象信息
  cout << car_1.description() << endl;
  cout << car_2.description() << endl;
  // 修改引擎
  car_2.setEngine("奔驰", 1);
  // 输出修改引擎以后的两个对象信息
  cout << car_1.description() << endl;
  cout << car_2.description() << endl;
  return 0;
}

Car::Car(const Car &other) {
  this->brand = other.brand;
  this->version = other.version;
  engine = new Engine(other.brand, other.version);
}