C++ Program Help! (Using classes)?

Question

I already have the class:
class Matrix{
public:
	int getrow() {return rows;};
	int getcol() {return cols;};
	char getname() {return name;};

	Matrix();
	~Matrix();

//	void Add(const Matrix &A, const Matrix &B);

private:
	int rows;
	int cols;
	char name;
	double *valuePtr;
	void setrow(int r){rows = (r>=0)? r : 0; };
	void setcol(int c){cols = (c>=0)? c : 0; };

};

//constructor: allocates memory for variables accordingly//
Matrix::Matrix(){
  rows = 0;
  cols = 0;
  name = 'A';
  *valuePtr = NULL;
  setrow(rows);
  setcol(cols);
}

// Input: data is a double matrix of size rows * columns //
Matrix::Matrix(int r, int c, char n, double *data){
   setrow(r);
   setcol(c);
   name = n;
   valuePtr = new double[rows*cols];
   for (int i=0; i<rows*cols; i++){
      valuePtr[i] = data


Code for the read function? How to run through the class accoridngly???

Silver_Sword · Accepted Answer

"double *valuePtr" is the wrong variable to use for a matrix. A matrix in your case is a dynamic 2-D array. Here is how you declare and initialize one:

double** valuePtr = new double*[rows];

for(int i = 0; i < rows; i++)
   valuePtr[i] = new double[cols];

// Now, "double *data" in your matrix constructor also needs 
// to be changed to "double** data". Then, here is how you
// copy  values from data into the matrix:

for(int i =0; i < rows; i++)
  for(int j =0; j < cols; j++)
     valuePtr[i][j] = data[i][j];

// In your first constructor, change " *valuePtr = NULL;" to
// "valuePtr = NULL;"

// If you need more help let me know

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C++ Program Help! (Using classes)?

1 Answer