Question

i have following class with overloading operators

#include<iostream>
#include<algorithm>
#include<math.h>
using namespace std;
class Cvector
{
public:
    int x,y;
    Cvector() {  x=0;y=0;}
    Cvector(int,int);
    Cvector operator+(Cvector);
    Cvector operator-(Cvector);
    int  operator*(Cvector);
    bool operator==(Cvector);
    Cvector operator*(int);
    Cvector operator=(Cvector);

    int cross_multiplication(Cvector,Cvector);
    float  norm();

    };
Cvector Cvector::operator=(Cvector a)
{
    x=a.x;
    y=a.y;
    return *this;

}
bool Cvector::operator==(Cvector b)
{
    return (x==b.x && y==b.y);

}

Cvector Cvector::operator*(int c)
{
    Cvector temp;
    temp.x=c*x;
    temp.y=c*y;
    return temp;

}
float Cvector::norm()
{
    float result=0;
    result+=x*x+y*y;;
    return sqrt(result);


}
Cvector::Cvector(int a,int b)
{
    x=a;
    y=b;

}
Cvector Cvector::operator+(Cvector a)
{
    Cvector temp;
    temp.x=x+a.x;
    temp.y=y+a.y;
    return temp;

}
Cvector Cvector::operator-(Cvector b)
{
    Cvector temp;
    temp.x=x-b.x;
    temp.y=y-b.y;
    return temp;

}
int Cvector::operator*(Cvector a)
{
    return x*a.x+y*a.y;


}

int main()
{
    Cvector a(3,4);
    Cvector b(4,5);
    cout<<b.norm()<<endl;
    Cvector c;
    c=a*b;
    cout<<(a==b)<<endl;

    return 0;
}

but it gives me one error

1>c:\users\dato\documents\visual studio 2010\projects\point_class\point_class\point_class.cpp(86): error C2679: binary '=' : no operator found which takes a right-hand operand of type 'int' (or there is no acceptable conversion)
1>          c:\users\dato\documents\visual studio 2010\projects\point_class\point_class\point_class.cpp(16): could be 'Cvector Cvector::operator =(Cvector)'
1>          while trying to match the argument list '(Cvector, int)'

please help me to fix this problem

Answer 1

Root Cause:

int Cvector::operator*(Cvector a)

returns an int, so:

c=a*b;

tries to assign an int to a Cvector object, which needs a overloaded = operator of Cvector class to take int as parameter, which it doesn’t. Hence the error.

Suggested Solution:

c has no business being a Cvector, it should be an int ideally, so either it could be a typo or it could indeed be the intent(which does break conventional algebraic wisdon).I am not sure which one it is.

If it is the former, just change type of c to int.

If it is latter, You need to provide a constructor which takes in an int parameter:

Cvector::Cvector(int)
{

}

This constructor will implicitly called to convert the int result of operator * and convert it to an Cvector object which will then be used to call the operator =.

Online Demo of your code with suggested solution