深层拷贝与浅层拷贝

Posted 2021-12-13 Roam-G

浅拷贝 实现对象间数据元素的一一对应复制。

深拷贝 当被复制的对象数据成员是指针类型时，不是复制该指针成员本身，而是将指针所指对象进行复制。

 

#include <iostream>
#include <cassert>
using namespace std;
class Point { 
   //类的声明同例6-16
   //……
};
class ArrayOfPoints {
   //类的声明同例6-18
   //……
};

int main() {
	int count;
	cout << "Please enter the count of points: ";
	cin >> count;
	ArrayOfPoints pointsArray1(count); //创建对象数组
	pointsArray1.element(0).move(5,10);
	pointsArray1.element(1).move(15,20);
	
	ArrayOfPoints pointsArray2(pointsArray1); //创建副本
	cout << "Copy of pointsArray1:" << endl;
	cout << "Point_0 of array2: " << pointsArray2.element(0).getX() << ", "
		<< pointsArray2.element(0).getY() << endl;
	cout << "Point_1 of array2: " << pointsArray2.element(1).getX() << ", "
		<< pointsArray2.element(1).getY() << endl;
	pointsArray1.element(0).move(25, 30);
	pointsArray1.element(1).move(35, 40);
	cout << "After the moving of pointsArray1:" << endl;
	cout << "Point_0 of array2: " << pointsArray2.element(0).getX() << ", "
		<< pointsArray2.element(0).getY() << endl;
	cout << "Point_1 of array2: " << pointsArray2.element(1).getX() << ", "
		<< pointsArray2.element(1).getY() << endl;

	return 0;
}

/*

运行结果如下：
Please enter the number of points:2
Default Constructor called.
Default Constructor called.
Copy of pointsArray1:
Point_0 of array2: 5, 10
Point_1 of array2: 15, 20
After the moving of pointsArray1:
Point_0 of array2: 25, 30
Point_1 of array2: 35, 40
Deleting...
Destructor called.
Destructor called.
Deleting...
接下来程序出现异常，也就是运行错误。

*/

 对象的深拷贝

#include <iostream>
#include <cassert>
using namespace std;
class Point { //类的声明同例6-16 ……
};
class ArrayOfPoints {
public:
   ArrayOfPoints(const ArrayOfPoints& pointsArray);
    //其他成员同例6-18        
};
ArrayOfPoints::ArrayOfPoints(const ArrayOfPoints& v) {
	size = v.size;
	points = new Point[size];
	for (int i = 0; i < size; i++)
		points[i] = v.points[i];
}
int main() {
	//同例6-20
}

/*
程序的运行结果如下：
Please enter the number of points:2
Default Constructor called.
Default Constructor called.
Default Constructor called.
Default Constructor called.
Copy of pointsArray1:
Point_0 of array2: 5, 10
Point_1 of array2: 15, 20
After the moving of pointsArray1:
Point_0 of array2: 5, 10
Point_1 of array2: 15, 20
Deleting...
Destructor called.
Destructor called.
Deleting...
Destructor called.
Destructor called.

*/