Error c2804 binary operator has too many parameters

#ifndef CLOCK_H
#define CLOCK_H
using namespace std;

class Clock
{
    //Member Variables

    private: int hours, minutes;

    void fixTime( );

    public:
        //Getter & settor methods.
        void setHours(int hrs); 
        int getHours() const;
        void setMinutes(int mins); 
        int getMinutes() const; 

        //Constructors
        Clock(); 
        Clock(int);
        Clock(int, int);
        //Copy Constructor
        Clock(const Clock &obj);
        //Overloaded operator functions
        void operator+(const Clock &hours);
        void operator+(int mins);
        void operator-(const Clock &hours);
        void operator-(int minutes1);
        ostream &operator<<(ostream &out, Clock &clockObj); //This however is my problem where i get the error C2804. Saying that it has to many parameters 
};
#endif

2

I’m learning about class operators and am stuck. I’m trying a simple class that defines an x,y point. The code then multiplies the x and y values of that point by 4 and spits out the new values. When I compile this, I get the following error on the line in bold:
«error C2804: binary ‘operator *’ has too many parameters»

Here is the code:

// 13.1.2.cpp : main project file.

#include «stdafx.h»
#include <iostream>
using namespace std;

class Point {
private:
int x,y; //Data Members

public:
//Constructors
Point() {x=0; y=0;}
Point(int new_x, int new_y) {set(new_x, new_y);}
Point(const Point &src) {set(src.x, src.y);}

//Operations
Point mult(const int &n, const Point &pt);
Point operator*(const int n, Point &pt) {return mult(n, pt);}

//Other member functions
void set(int new_x, int new_y);
int get_x() const {return x;}
int get_y() const {return y;}
};

int main()
{
Point point1(20, 25); //Create a new Point objects
Point point2 = 4 * point1; //Create another new point that is 4x the value of point1

cout << «The value of point2 is » << point2.get_x();
cout << «, » << point2.get_y() << «.» << endl << endl;

system(«PAUSE»);
return 0;
}

void Point::set(int new_x, int new_y) {
x = new_x;
y = new_y;
}

Point Point::mult(const int &n, const Point &pt) {
Point new_pt;
new_pt.x = n * pt.x;
new_pt.y = n * pt.y;
return new_pt;
}

Does anyone see why this is happening? Thanks!

OK….you have a few mistakes. I don’t know whether you know this but… Your operator* definition is wrong. When you call it like you did here:Point point2 = 4 * point1; compiler turns that intopoint1.operator*(4); which, of course, doesn’t match parameters declared in operator* prototype. Operator* is binary, which means it needs 2 operands, and because you declared it within class Point (not as global function), you don’t need to pass object explicitly. So:

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class Point
{

//......

//Operations
Point mult(int n );
Point operator*(int n) {return mult(n);}
//.....
};

int main()
{
//....

Point point2 = point1 * 4; //Create another new point that is 4x the value of point1

//.....

return 0;
}

//....

Point Point::mult(int n) {
Point new_pt;
new_pt.x = n * (*this).x;//uses dereferenced this pointer
new_pt.y = n * (*this).y;//uses dereferenced this pointer
return new_pt;
}

Thank you. I’m not surprised about the multiple mistakes. One other mistake that I made was not explaining the point of the exercise that I am working on. This is an exercise that has two objectives: 1) to learn about global / friend functions and 2) about improving efficiency with references. So, I need to keep those ideas in my code, even though I don’t think that I did with my original post.

I’m totally confused about how to do this, and I think that the book that I am studying does a terrible job explaining it. Can somebody see what I am doing wrong in my original code with these two ideas?

Thanks again!

• Remove From My Forums

• Вопрос

• Hey Folks,

  I wonder if someone could answer this…

  Here’s the interface of an oversimplified Matrix class…

  template<typename T>
  class Matrix {
  public:
      Matrix() {}    
      ~Matrix() {}
      Matrix<T>& Matrix<T>::operator=(Matrix<T>&&);
      friend const Matrix<T> operator+(const Matrix<T>&, const Matrix<T>&);
      friend ostream& operator<<(ostream&, Matrix<T>&);
  private:
      vector<vector<T>> _mat;
  };

  No problems when I implement the equality operator…

  template<typename T>
  Matrix<T>& Matrix<T>::operator=(Matrix<T>&& other) {
      swap(_mat, other._mat);    
      return *this;
  }

  No problems when I implement the dump-to-output-stream operator…

  template<typename T>
  ostream& operator<<(ostream& os, Matrix<T>& mat) {
      ostream_iterator<T> out(os, » «);
      vector<T> vec(0);    
      for (int i = 0; i < mat.Rows(); ++i) {
          vec = mat.getRow(i);
          copy(vec.begin(), vec.end(), out);
          os << endl;
      }
      return os;
  }

  But, when implementing the plus operator outside the interface…

  template<typename T>
  const Matrix<T> Matrix<T>::operator+(const Matrix<T>& left, const Matrix<T>& right) {
      // …
      Matrix<T> res;
      return res;
  }

  Compiler gives me…

  error C2039: ‘+’: is not a member of ‘Matrix<T>’

  And removing the ‘friend’ prefix results in…

  error C2804: binary ‘operator +’ has too many parameters.

  I can get it to compile and work properly if the definition is stated inside the class interface.

  I’ve used a General -> Empty project.

  By the way, the compiler being used is the latest — Visual C++ Compiler November 2013 CTP.

  Any thoughts as to why this is happening?

Записывая свой собственный векторный класс (для игрового движка) и перегружая оператор ‘+’ в проекте Visual Studio 2013 CPlusPlus (используя VC runtime 120), он вызывает ошибку компилятора:

Ошибка: слишком много параметров для этой операторской функции.

Фрагмент кода из Vector.hpp файл ниже.

Vector.hpp

class Vector
{
private:
double i;
double j;
double k;
public:
Vector(double _i, double _j, double _k)
{
i = _i;
j = _j;
k = _k;
}

Vector& operator+=(const Vector& p1)
{
i += p1.i;
j += p1.j;
k += p1.k;
return *this;
}

//Some other functionality...

Vector operator+(const Vector& p1, Vector& p2) //Error is thrown here...
{
Vector temp(p1);
return temp += p2;
}
};

Что я здесь не так делаю? Не хочу, чтобы мой оператор перегружал функцию, не являющуюся членом.

3

когда operator+ определяется внутри класса, левый операнд оператора является текущим экземпляром. Итак, чтобы объявить перегрузку operator+ у вас есть 2 варианта

• внутри класса, только с одним параметром, который является правым операндом
• вне класса, с двумя параметрами, левый и правый операнды.

Выбор 1: вне класса

class Vector
{
private:
double i;
double j;
double k;
public:
Vector(double _i, double _j, double _k)
{
i = _i;
j = _j;
k = _k;
}

Vector& operator+=(const Vector& p1)
{
i += p1.i;
j += p1.j;
k += p1.k;
return *this;
}

//Some other functionality...};

Vector operator+(const Vector& p1, const Vector& p2)
{
Vector temp(p1);
temp += p2;
return temp;
}

Выбор 2: внутри класса

class Vector
{
private:
double i;
double j;
double k;
public:
Vector(double _i, double _j, double _k)
{
i = _i;
j = _j;
k = _k;
}

Vector& operator+=(const Vector& p1)
{
i += p1.i;
j += p1.j;
k += p1.k;
return *this;
}Vector operator+(consr Vector & p2)
{
Vector temp(*this);
temp += p2;
return temp;
}

};

Вы можете увидеть, как должны быть объявлены операторы здесь: Операторы C / C ++

10

Еще одна возможность — использование ключевого слова friend.

friend Vector operator+(const Number& n1, const Number& n2)
{
Vector temp(n1);
temp+=n2;
return temp;
}

0

Опять шаблоны классов

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