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conversion problem

masterinex (181)
When i run this code, I am getting :

Error C2664 'void Coord<double>::setX(const Coord<double> &)': cannot convert argument 1 from 'double' to 'const Coord<double> &' CartesianCoord


for this line :


b3.setX( b1.getX() - b2.getX() );

in my Source.cpp file.



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Header:

#pragma once


template <typename T> 
class Coord {

public:

	T x_;
	T y_;

	Coord()
	{
		x_ = 0.0;
		y_ = 0.0; 

	}


	// 2 args constructor 
	Coord(T x  , T y ) : x_(x) , y_(y) {}

	// allows operator - to access private fields outside of class 
	//friend Coord<T> operator - (const Coord  <T> &  b1, const Coord  <T> & b2); 

	// does not work 
	//friend ostream & operator << (ostream & os,  const Coord & c);

	T getX() const 
	{
		return x_;
	}

	T getY() const 
	{
		return y_;
	}

	 void setX(Coord  <T> const &  c)
	 {
		 x_ = c.getX(); 
	 }


	 void setY(Coord  <T> const &  c)
	 {
		 y_ = c.getY();
	 }


	double& magnitude( const Coord & c )
	{
		double magnitude = c.x_ * c.x_ + c.y_ * c.y_; 
		magnitude = sqrt(magnitude); 
		return magnitude; 
	} 

	// unary minus operator 
	Coord operator-()
	{
		this->x_ = (-1) * x_;
		this->y_ = (-1) * y_;

		return *this; 
	}




};


Source.cpp:

# include <iostream>
# include "coord.hpp"
using namespace std;


//template <typename T>
//Coord<T> operator - (const Coord  <T> &  b1, const Coord  <T> & b2) {
//	Coord <T> b3;
//	b3.x_ = b1.x_ - b2.x_;
//	b3.y_ = b1.y_ - b2.y_;
//	return b3;
//}


//template <typename T>
//Coord<T> operator - ( Coord  <T> &  b1,  Coord  <T> & b2) {
//	Coord <T> b3;
//	b3.x_ = b1.getX() - b2.getX();
//	b3.y_ = b1.getY() - b2.getY();
//	return b3;
//}



template <typename T>
Coord<T> operator - (Coord  <T> &  b1, Coord  <T> & b2) {
	Coord <T> b3;
	b3.setX( b1.getX() - b2.getX() );
	b3.setY( b1.getY() - b2.getY() );
	return b3;
}



template <typename T>
ostream & operator << (ostream & os,  Coord <T> & c)
{
	os << "(" << c.getX() << "," << c.getY() << ")" << endl; 
	
	return os; 

}



int main()
{
	Coord <double>  a(3, 3);
	Coord <double> b(2, 2);

	Coord <double> c;

	c = a - b; 

	cout << "c is " << c << endl; 

	int magnitude;
	magnitude = c.magnitude(c);

	cout << " The magnitude of c is " << magnitude << endl;

	Coord <double> d;

	d = -c; 

	cout << " d is " << d << endl; 


}
Chervil (7320)

The setX() function expects a parameter of type Coord <T>. But you try to pass a parameter of type T. You might consider changing the setX() and setY() to match the way you intend to use it. It probably doesn't make a lot of sense to pass a Coord object there in any case.
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    void setX( T x )
    {
        x_ = x; 
    }


Or maybe do something like this:
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template <typename T>
Coord<T> operator - (const Coord  <T> &  b1, const Coord  <T> & b2) 
{
	Coord <T> b3 ( b1.getX() - b2.getX(), b1.getY() - b2.getY() );
	
	return b3;
}

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