具有友元函数和运算符重载的 C++ 模板

Question

我一直在将 C++ 模板添加到现有的运算符重载程序中，现在我遇到了这些错误。我无法纠正这些错误，任何人都可以帮助我...... 这是代码... 我可以在简单的重载函数上做模板，但在友元函数上有问题.. *****************注意：（更新）整改后的代码... /演示运算符过载的程序/ #include

template <class T>
class OP 
{
    T x, y, z;

    public:

    void IN()
    {
        std::cout << "Enter three No's : ";
        std::cin >> x >> y >> z;
    }

    void OUT()
    {
        std::cout << std::endl << x << " " << y << " " << z;
    }
    void operator~();
    void operator+(int);                    //Can accept both one or two argument

    template<class TA>
    friend void operator++(OP<T>);             //Accept one arguments (Unary Operator);

    template<class TB>
    friend void operator-(OP<T>, int);     //Accept two arguments     (Binary Operator)

    template<class TC>
    friend void operator!=(OP&, char t);
};

template<class T>
void OP<T>::operator~() //Unary Member Operator
{
    std::cout << std::endl << " ~ (tilde)";
}

template<class T>
void OP<T>::operator+(int y)    //Binary Member Operator
{
    std::cout << std::endl << "Argument sent is " << y;
}

template<class T>
void operator-(OP<T> &a, int t) //Binary Friend Operator
{
    a.x= a.x-t;
    a.y= a.y-t;
    a.z= a.z-t;
}

template<class T>
void operator!=(OP<T> &q, char t)   //Binary Friend Operator
{
    std::cout << std::endl << "Char " << t; 
}

template<class T>
void operator++(OP<T> x)    //Unary Friend Operator
{
    std::cout << std::endl << "Friend Unary Operator";
}

int main()
{
    OP <int> n, m;
    n.IN();
    m.IN();
    m+1;
    n!='t';
    int a = 1;
    char r='r';
    ~n;         //Member Function (Unary)
    n-a;        //Member Function (Unary)
    operator-(m, a);    //Friend Function (Binary)
    operator++(m);  //Friend Function (Unary)
    n.OUT();
    m.OUT();
    std::cin.get();
    return 0;
}

三个友元函数都出错，错误是

Now my friend function is not able to access the private member...<<< Please tell me what I'm doing wrong...

Answer 1

如果您在模板 class 中声明友元函数，您必须在模板 class 定义中提供定义，或者在模板外重新声明它模板 class.

在模板中将其声明为友元 class 不会在封闭范围内声明该函数。

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