对象赋值-赋值运算符重载
赋值运算符函数是在类中定义的特殊的成员函数
典型的实现方式：
ClassName& operator=(const ClassName &right)
{
if (this != &right)
{
//将right的内容复制给当前的对象
}
return *this;
}
#include <iostream>
using namespace std; class Test
{
int id;
public:
Test(int i) :id(i) { cout << "obj_" << id << "created\n"; }
Test& operator= (const Test& right)
{
if (this == &right)
cout << "same obj!" << endl;
else
{
cout << "obj_" << id << "=obj_" << right.id << endl;
this->id = right.id;
}
return *this;
}
}; int main()
{
Test a(), b();
cout << "a = a:";
a = a;
cout << "a = b:";
a = b;
return ;
}
流运算符重载函数的声明
istream& operator>>(istream& in, Test& dst);
ostream& operator<<(ostream& out, const Test& src);
备注：
函数名为：
operaotor>>和operator<<
返回值为：
istream& 和ostream&,均为引用
参数分别：流对象的引用，目标对象的引用。对于输出流，目标对象还是常量
#include <iostream>
using namespace std; class Test
{
int id;
public:
Test(int i) :id(i)
{
cout << "obj_" << id << "created\n";
}
friend istream& operator >> (istream& in, Test& dst);
friend ostream& operator << (ostream& out, const Test& src);
};
//备注：以下两个流运算符重载函数可以直接访问私有成员，原因是其被声明成了友元函数
istream& operator >> (istream& in, Test& dst)
{
in >> dst.id;
return in;
} ostream& operator << (ostream& out, const Test& src)
{
out << src.id << endl;
return out;
} int main()
{
Test obj();
cout << obj;
cin >> obj;
cout << obj;
}