正在学习C++来自Java世界的中级开发人员...
现在我正在尝试学习如何进行运算符重载
即使我在网上搜索了很多,所以:
如何正确重载 ostream 的 <<运算符?
https://stackoverflow.com/a/476483/982161
这是我的参考:
举这个例子:
// overload_date.cpp
// compile with: /EHsc
#include <iostream>
using namespace std;
class Date
{
int mo, da, yr;
public:
Date(int m, int d, int y)
{
mo = m; da = d; yr = y;
}
friend ostream& operator<<(ostream& os, const Date& dt);
};
ostream& operator<<(ostream& os, const Date& dt)
{
os << dt.mo << '/' << dt.da << '/' << dt.yr;
return os;
}
int main()
{
Date dt(5, 6, 92);
cout << dt;
}
但是我希望/需要使用标头和实现的分离来开发它
我的代码
页眉
#ifndef POINT_H
#define POINT_H
#include <ostream>
class Point
{
public:
Point();
virtual ~Point();
unsigned int Getx();
unsigned int Gety();
void Setx(unsigned int val);
void Sety(unsigned int val);
friend std::ostream& operator<<(std::ostream& ostream, const Point& dt);
private:
unsigned int x;
unsigned int y;
};
#endif // POINT_H
实现
#include "Point.h"
#include <ostream>
Point::Point()
{
x = 1u;
y = 1u;
}
Point::~Point()
{
//dtor
}
unsigned int Point::Getx()
{
return x;
}
unsigned int Point::Gety()
{
return y;
}
void Point::Setx(unsigned int val)
{
x = val;
}
void Point::Sety(unsigned int val)
{
y = val;
}
std::ostream& operator<<(std::ostream& out, const Point& a) {
return out << "A(" << a.Getx() << ", " << a.Gety() ")";
}
我无法编译收到此错误的代码:
include\Point.h|24|error:将"const Point"作为"this"参数传递 'unsigned int Point::Getx((' 丢弃限定符 [-fpermissive]|
使代码编译的两件事:
第一:你的getter应该是恒定的。
unsigned int Getx() const;
unsigned int Gety() const;
unsigned int Point::Getx() const
{
return x;
}
unsigned int Point::Gety() const
{
return y;
}
第二:
更正被覆盖方法的返回:
return out << "A(" << a.Getx() << ", " << a.Gety() << ")";
(您错过了最后一个"<<"(。