Question

I am studying classes in c++ and i came across this snippet of code and i wondering what param was used for.

// vectors: overloading operators example
#include <iostream>
using namespace std;

class CVector {
  public:
    int x,y;
    CVector () {};
    CVector (int,int);
    CVector operator + (CVector);
};

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

CVector CVector::operator+ (CVector param) {
  CVector temp;
  temp.x = x + param.x;
  temp.y = y + param.y;
  return (temp);
}

int main () {
  CVector a (3,1);
  CVector b (1,2);
  CVector c;
  c = a + b;
  cout << c.x << "," << c.y;
  return 0;
}

Answer 1

Param is the right operand of the + operator.

Here is cleaner version of the code:

#include <iostream>
using namespace std;

class CVector {
  public:
    int x,y;
    CVector ();
    CVector (int,int);
    CVector (const CVector&);
    CVector operator + (const CVector&) const;
};

CVector::CVector() : x(0), y(0) {}
CVector::CVector(int a, int b) : x(a), y(b) {}
CVector::CVector(const CVector& v) : x(v.x), y(v.y) {}

CVector CVector::operator+ (const CVector& param) const {
  CVector temp(*this);
  temp.x += param.x;
  temp.y += param.y;
  return (temp);
}

int main () {
  CVector a (3,1);
  CVector b (1,2);
  CVector c;
  c = a + b;
  cout << c.x << "," << c.y;
  return 0;
}