[] overload for matrix

[Marco Schneider]

Hello
I have a question.
I tried to overload the [] operator  for  a class matrix
I wanted to use it to  change the private elements so that it is
possible to write
m[2][3] = 10;    for exampel if  -m-  is a object of the class matrix

This worked fine with array as written in the exampel below

double & operator[](int z);      // header
double &  array::operator[](int z)
{
   return m[z];
}

The problem with matrixes is, that the [] operator accepts only one
Argument
and i found no way  to change this. Is this possibel or not ???

Below there is a short part of the program I tried to run.
class matrix
{
private:
   unsigned long row;
   unsigned long colum;
   double * m;
public:
   double & operator[](int r,int c);
};
//  class funktion
double & matrix::operator[](int c,int r)
{
   return m[row * c + r];
}

I would be very happy about any kind of help.
With many thanks in advance.
Marco