首先拷贝构造函数的声明方法:
类名::类名(const 类名&)
1、浅拷贝的实现程序:
#include "stdafx.h"
#include <iostream>
#include <cstring>
using namespace std;
class Person
{
public:
//构造函数
Person(const char *name, double hei, double wei,
int age0):height(hei),weight(wei),age(age0){
cout << "Person ctor called .\n";
pName = new char[strlen(name) + 1];
strcpy(pName, name);
}
//析构函数
~Person(){
cout << "deleting pName";
delete[] pName; }
//类Person的拷贝构造函数
Person(const Person &person){
cout << "Person copy ctor called";
pName = person.pName;
height = person.height;
weight = person.weight;
age = person.age;
}
private:
char *pName;
double height;
double weight;
int age;
}; int main()
{
Person p1("Leekin",175,185,25);
Person p2(p1);
return 0;
}
首先这个程序在VS2013上面编译不通过;是因为浅拷贝存在风险:非法操作内存,究其原因是因为“拷贝不充分”导致堆中的某一块内存被不同对象的指针属性同时指向,该内存不可避免的被释放多次,这是不应许。第一次被释放的空间已经属于操作系统,当在一次释放时那一片空间已经不属于程序了。
以下是浅拷贝的内存模型:
2、深拷贝可以避免由于浅拷贝带来的问题,即让拷贝函数做好充分的拷贝,程序如下:
#include "stdafx.h"
#include <iostream>
using namespace std;
class Person
{
public:
//构造函数
Person(const char *name, double hei, double wei,
int age0):height(hei),weight(wei),age(age0){
cout << "Person ctor called .\n";
pName = new char[strlen(name) + 1];
strcpy(pName, name);
}
//析构函数
~Person(){
cout << "deleting pName";
delete[] pName; }
//类Person的拷贝构造函数
Person(const Person &person){
cout << "Person copy ctor called";
pName = person.pName;
height = person.height;
weight = person.weight;
age = person.age;
//深拷贝:重新申请一块内存
pName = new char[strlen(person.pName) + 1];
strcpy(pName, person.pName);
}
private:
char *pName;
double height;
double weight;
int age;
}; int main()
{
Person p1("Leekin",17.5,18.5,25);
Person p2(p1);
return 0;
}
深拷贝的内存模型: