help with a snippet

Alright, i have starred at this for sometime, and while i could try every combination of const modifier, I would rather get an explanation why this won't go. I still get hung up on const stuff...

Code:

---

Matrix& Matrix::operator = (const Matrix& m) {
        if (*this == m) {
                for (int r = 0; r < rows(); r++) {
                        for (int c = 0; c < cols(); c++) {
                                (*this)(r,c) = m(r,c);
                        }
                }
                return *this;
        } else {
                throw std::invalid_argument("Error! Matricies must be equal for assignment.");
        }
}

---

I get the following error on compile:

Quote:

---

error C2662: 'cols' : cannot convert 'this' pointer from 'const class Matrix' to 'class Matrix &'
Conversion loses qualifiers
error C2662: 'rows' : cannot convert 'this' pointer from 'const class Matrix' to 'class Matrix &'
Conversion loses qualifiers

---

Thanks in advance!

The error refers to cols() and rows(), but you didn't post what these are. I get no errors with the following code:

Code:

---

class Matrix
{
  public:
      int nRows;
      int nCols;
      int rows() const { return nRows; }
      int cols() const { return nCols; }
 
      Matrix& operator = (const Matrix& m);
};

Matrix& Matrix::operator = (const Matrix& m)
{
    int r = rows();
    return *this;
}

---

Regards,

Paul McKenzie

I apologize for the incompleteness of my problem, but I thought it had to do with something i did wrong in that function. Here were the original definitions for that class (exactly as you had guessed):

in header file:

Code:

---

public:
int rows() {return m_nRows;};
int cols() {return m_nCols;};

private:
int m_nRows, m_nCols;

---

So now i have modifed rows() and cols() to match yours and everything works perfectly. So correct me if I am wrong, but placing the const in rows() and cols() function makes what rows() and cols() pass back const?

Thanks for the assisstance!