Thread: Overloading array operator

Hello all,

I know it is possible to overload the bracket symbol '[]', and I know how to do it. I was wondering, is it possible to overload the double-bracket symbol? I have a matrix class. I am doing the following:

Code:

class Matrix
{
   ...
   double** operator[][](int&, int&);
   ...
};

Does this seem right, such that I can do something like the following in my main program?

Code:

Matrix A;
... //assign some values
cout<<A[2][2];

Thanks.

Bill

Compile and see.

Sorry I forgot to mention that I did compile and I am getting errors. Here is all the code:

Code:

//#include "Complex.h"

class Matrix
{
	int row,col;
	Complex **A;
	bool empty;
public:
	Matrix();
	Matrix(const int&, const int&);
	~Matrix();
	Matrix operator*(const Matrix&);
	Complex** operator[][](int&, int&);
};

Matrix::Matrix()
{
	row = col = 0;
	empty = true;
}

Matrix::Matrix(const int &a, const int &b)
{
	row = a;
	col = b;

	empty = false;

	A = new Complex* [row];
	for (int i=0; i<row; i++)
		A[i] = new Complex[col];
	
	for (i=0; i<row; i++)
	{
		for(int j=0; j<col; j++)
		{
			A[i][j] = 0;		//zero-out the entire matrix;
		}
	}
}

Matrix::~Matrix()
{
	if(!empty)
	{
		for (int i=0; i<row; i++)
			delete[] A[i];
		delete[] A;
	}
}

Complex** Matrix::operator[][](int &a, int &b)
{
	return A[a][b];
}

Matrix Matrix::operator*(const Matrix &another)
{
	//still didn't do this one
}

The following errors occur pointing to the function prototype and the first bracket of the function definition:

Code:

Error C2092: array element type cannot be function

The last error says "cannot recover from previous errors; stopping compliation."

>> is it possible to overload the double-bracket symbol?

No. You have to overload operator[] to return something that has its own operator[] overloaded to return a value. It is somewhat complicated.

You can also just use a regular function that takes two parameters.