I am fairly new to the concept of inheritance, and I am constructing a
Matrix
class and a derived
SquareMatrix
class. Some of my methods depend on safely casting a Matrix to a SquareMatrix. I have heard of something called copyconstructors, but I don't think they work the way I have tried to use them. I tried to use
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SquareMatrix::SquareMatrix(const Matrix& A)
: Lptr(0), Uptr(0), Pptr(0), multiplier(1), determinant(0)
{
this>matrixData = A.matrixData;
}
 
but, for some reason, it is saying that my
Matrix::matrixData
is bad! (and I KNOW this is simply not the case, as it has worked for BOTH classes in my other methods). I wish to, without using the heap, make a copy constructor so that I can safely make a Matrix a SquareMatrix. I was about to use some of the casting techniques here,
http://www.cplusplus.com/doc/tutorial/typecasting/ , namely this one:
*(dynamic_cast<SquareMatrix*>(this>getTranspose()))
in the place of
this>getTranspose()
, for example, but I don't know if it has to be on the heap (I wish to AVOID putting it on the heap, as both classes will have so many methods).
Is there any safe way around this problem? (Note: I could always do a
reinterpret_cast
, but from the aforementioned article, it is a means to an end.
EDIT:
My declaration of matrixData is, of course, in base class, Matrix, and is declared as:
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protected:
std::vector<std::vector<long double> > matrixData;
 
The error I am getting is:
error: 'std::vector<std::vector<long double, std::allocator<long double> >, std::allocator<std::vector<long double, std::allocator<long double> > > >
within this context

It signals the error from Matrix.h, even though SquareMatrix is supposed to have it as well.
If it helps any, here is the full code in both Matrix.h, SquareMatrix.h:
Matrix.h
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#ifndef MATRIX_H
#define MATRIX_H
#include <iostream>
#include <vector>
class Matrix
{
public:
Matrix();
Matrix(const std::vector<std::vector<long double> >&);
~Matrix(); //for releasing any dynamically allocated memory
//getter functions
unsigned getRowCount() const;
unsigned getColumnCount() const;
//for transposing a Matrix
Matrix getTranspose() const;
static Matrix transpose(const Matrix&);
//returns filled Matrix
static Matrix createFilledMatrix(unsigned, unsigned, long double);
//overloading operators to simplify Matrix arithmetic
Matrix operator+(const Matrix&);
Matrix operator(const Matrix&);
Matrix operator*(const Matrix&);
Matrix operator*(long double);
friend Matrix operator(const Matrix&);
friend Matrix operator*(long double, const Matrix&);
friend std::ostream& operator<<(std::ostream& , const Matrix& );
protected:
std::vector<std::vector<long double> > matrixData;
virtual void validateData();
//members
private:
//still trying to decide on how to implement pseudoInverse(), inverse.
//My best bet here would be to make it all private and force the user of this code to make a friend function/class to get
//it. Either way, I will need a destructor.
};
#endif // MATRIX_H
 
SquareMatrix.h
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#ifndef SQUAREMATRIX_H
#define SQUAREMATRIX_H
#include "Matrix.h"
#include <vector>
class SquareMatrix : public Matrix
{
public:
SquareMatrix();
SquareMatrix(const Matrix&);
SquareMatrix(std::vector<std::vector<long double> >);
virtual ~SquareMatrix(); //remember, we are responsible for freeing any dynamic memory we explicitly use
//the SquareMatrix version of createFilledMatrix()
static SquareMatrix createFilledMatrix(unsigned, long double);
//convenient member functions exclusive to SquareMatrix
bool isUpperTriangularMatrix() const;
bool isLowerTriangluarMatrix() const;
bool isDiagonalMatrix() const;
static SquareMatrix identityMatrix(unsigned);
long double computeDeterminant();
//getter version of computeDeterminant() which allows for efficient retrieval later (after computeDeterminant() has been called)
long double getDeterminant() const;
void PLUDecompose();
//getter functions
SquareMatrix getL() const;
SquareMatrix getU() const;
SquareMatrix getP() const;
protected:
void validateData();
private:
SquareMatrix *Lptr, *Uptr, *Pptr; //should be initialized by LUDecompose before using
long double determinant;
int multiplier;
};
#endif // SQUAREMATRIX_H
 