C++ 链接器错误（link2005、link1169）

我在尝试编译时遇到以下错误：

我真的很努力地解决所有的错误，但那三个赢了。我试了4个小时，因为我是初学者。我非常感谢你们的帮助

(一)

错误1错误LNK2005:“类std:：basic_istream>&类cdecl cs52:：operator>>（类std:：basic_istream>&类cs52:：SwimmingPool&）”（？5cs52@@YAAAV？$basic_istream@DU？$char_traits@D@std@@@std@@AAV12@AAVSwimmingPool@0@@Z）已在POOL.obj中定义

(二)

---

错误2错误LNK2005：“类std:：basic_ostream>和&uu cdecl cs52:：operator正在工作…”您在头文件中定义了

operator

自由函数。这导致实现被编译到两个对象文件中，从而导致重复的定义

你必须：

将它们声明为

inline

在CPP文件中移动实现

使重载方法成为类的成员，并直接在类定义体中实现它们（这实际上使它们成为内联的）

选项1使编译器不定义函数，而是将其实现复制到调用它的任何地方。当它是编译到DLL中的API的一部分时，可能会导致问题。交换DLL时，函数的更改不会影响现有程序，因为实现在主工件中（二进制兼容性被破坏）

在我看来，选项2是最好的选项，因为它将操作符实现绑定到类实现

---

选项3在您的情况下不起作用，因为这样您的类必须是操作符的LHS（操作符重载方法将在您的类的对象上调用）。输入/提取运算符不是这样。

顺便说一句，您的实现也应该与声明在同一个名称空间中，所以在您的第一个cpp文件中这样做：名称空间cs52{//your code here}非常感谢您，我的代码终于活了起来，感谢您：D

#ifndef POOL_H
#define POOL_H
#include<iostream>


namespace cs52
{
    class SwimmingPool{



    public:
        SwimmingPool(int size);
        void fill(int amount);
        void splash();
        void swim();
        void evaporate(int amount);
        int getSize();
        int getContents();
        void setSize(int size);


    private:
        int mySize; // in gallons
        int myContents; // in gallons

        friend std::ostream& operator<<(std::ostream& outs, const SwimmingPool & pool);
        friend std::istream& operator>>(std::istream& ins, SwimmingPool & pool);
        friend SwimmingPool operator +(SwimmingPool& d, SwimmingPool& d2);
        friend SwimmingPool operator -(SwimmingPool& d, SwimmingPool& d2);

    };
    bool operator >(SwimmingPool& d, SwimmingPool& d2);
    bool operator <(SwimmingPool& d, SwimmingPool& d2);
    bool operator ==(SwimmingPool& d, SwimmingPool& d2);
    bool operator !=(SwimmingPool& d, SwimmingPool& d2);

    std::ostream& operator<<(std::ostream& outs, const SwimmingPool & pool){

        outs << "size " << pool.mySize << " contents " << pool.myContents;

        return outs;
    }
    std::istream& operator>> (std::istream& ins, SwimmingPool & pool)

    {
        std::cout << "enter size of pool\n";
        ins >> pool.mySize;
        pool.myContents = 0;
        return ins;
    }

}
#endif

#include "POOL.h"
using namespace std;
using namespace cs52;
SwimmingPool::SwimmingPool(int size)
    {
        mySize = size;
        myContents = 0;
    }


void SwimmingPool::fill(int amount)
    {
        myContents += amount;

    }

    void SwimmingPool::splash()
    {
        cout << "splash" << std::endl;
    }


    void SwimmingPool::evaporate(int amount)
    {
        myContents -= amount;
    }


    int SwimmingPool::getSize()
    {
        return mySize;
    }


    int SwimmingPool::getContents()
    {
        return myContents;
    }

    void SwimmingPool::swim()
    {
        cout << "swimming\n";
    }
    bool cs52::operator >(SwimmingPool& d, SwimmingPool& d2)
    {
        if (d2.getSize() <d.getSize())
        {
            return true;
        }
        return false;
    }
    bool cs52::operator <(SwimmingPool& d, SwimmingPool& d2)
    {
        if (d2.getSize() >d.getSize())
        {
            return true;
        }
        return false;
    }
    bool cs52::operator ==(SwimmingPool& d, SwimmingPool& d2)
    {
        if (d2.getSize() == d.getSize())
        {
            return true;
        }

        return false;
    }
    bool cs52::operator !=(SwimmingPool& d, SwimmingPool& d2)
    {
        if (d2.getSize() != d.getSize())
        {
            return true;
        }

        return false;
    }

    SwimmingPool cs52::operator +(SwimmingPool& d, SwimmingPool& d2)
    {
        SwimmingPool s(d.getSize() + d2.getSize());
        s.fill(d.getContents() + d2.getContents());
        return s;
    }
    SwimmingPool cs52::operator -(SwimmingPool& d, SwimmingPool& d2)
    {
        if (d.getSize() >= d2.getSize() && d.getSize() >= d2.getSize())
        {
            SwimmingPool s(d.getSize() - d2.getSize());
            s.fill(d.getContents() - d2.getContents());
            return s;
        }
        else
            cout << "ERROR\n";
        return 0;
    }

#include "POOL.h"
#include<iostream>

using namespace std;
using namespace cs52;
int main()
{
    SwimmingPool smallOne(1);
    SwimmingPool bigOne(1000);
    bigOne.fill(100);
    SwimmingPool yours(10);
    yours.fill(1);
    SwimmingPool mine(20);
    mine.fill(19);


    cout << "--some tests follow--" << endl;
    SwimmingPool pool1 = mine + mine;
    SwimmingPool pool2 = yours - yours;
    if (pool1 > pool2) {
        cout << "> is working..." << endl;
    }
    if (pool1 != pool2) {
        cout << "!= is working..." << endl;
    }
    if (pool2 < pool1) {
        cout << "< is working..." << endl;
    }
    if (pool1 == pool1) {
        cout << "== is working..." << endl;
    }
    cout << "---printing pool1---" << endl;
    cout << pool1 << endl;
    cout << "---printing pool2---" << endl;
    cout << pool2 << endl;
    cout << "---reading pool1---" << endl;
    cin >> pool1;
    cout << "---printing a revised pool1---" << endl;
    cout << pool1 << endl;
    cout << "---some broken code follows---" << endl;;
    SwimmingPool badPool = smallOne - bigOne;
    system("pause");
    return 0;
}