赋值运算符重载
代码语言：javascript复制#include<iostream>
using namespace std;
class wood {
public:
wood(int num) {
this->num = new int(num);
cout << "构造函数调用" << endl;
}
//赋值运算符重载（赋值拷贝）
wood& operator=(wood& w1) //w1是要进行拷贝的值
{
//浅拷贝
//num = w.num;
//深拷贝
//防止自赋值
if (this != &w1)
{
//如果本身已经在堆区开辟内存，就先释放
if (num != NULL)
{
delete num;
num = NULL;
}
num = new int(*w1.num);
return *this;
}
}
//析构函数
~wood() {
if (num != NULL)
{
delete num;
num = NULL;
}
cout << "析构函数调用" << endl;
}
int* num;
};
void test()
{
wood w(10);
cout << *w.num << endl;
wood w1(20);
w1 = w;
cout << *w1.num << endl; //在析构函数里面写了delete语句释放内存后，就会造成内存的重复释放，需要进行深拷贝操作
}
int main()
{
test();
return 0;
}注意：
代码语言：javascript复制#include<iostream>
using namespace std;
class wood {
friend ostream& operator<<(ostream& cout, wood wood);
public:
wood(int num) {
this->num = new int(num);
cout << "构造函数调用" << endl;
}
//析构函数
~wood() {
if (num != NULL)
{
delete num;
num = NULL;
}
cout << "析构函数调用" << endl;
}
private:
int* num;
};
ostream& operator<<(ostream& cout, wood wood)
{
cout << "木头的数量为:" << *wood.num << endl;
return cout;
}
void test()
{
wood w(10);
cout << w << endl;
}
int main()
{
test();
return 0;
}当加入了左移重载函数后，在输出cout<<时就已经调用了w的析构函数释放了内存，所以在cout<<w<<endl;会发生错误
