Array subscript operator on a Matrix - c++

Question

I'm trying to overload the Array subscript operator on a Matrix, however I'm getting an error that I can't understand. The CMazeSquare && operator[] (const tuple &other); is meant to access the CMazeSquare grid** which a matrix of CMazeSquares. I would like to be able to access the CMazeSquare object just by saying grid[someTuple]
CMaze.h:61:17: error: expected unqualified-id before ‘&&’ token
CMazeSquare && operator [] (const tuple &other);
^
I can't for the life of me understand what is wrong here. Please help.
#ifndef CMAZE_H
#define CMAZE_H
struct tuple
{
short x;
short y;
tuple();
tuple(const tuple &other);
tuple(short X, short Y);
tuple operator + (const tuple &other);
};
class CMaze
{
public:
private:
struct CMazeSquare
{
CMazeSquare ();
void Display (ostream & outs);
sType what;
bool vistited;
};
CMazeSquare ** grid;
CMazeSquare && operator [] (const tuple &other); //<- This is the problem
};
#endif
I'm thinking the implementation of the operator would look something like this:
//in CMaze.cpp
CMaze::CMazeSquare && CMaze::operator [](tuple &other)
{
return this[other.x][other.y];
}

Answer 1

This is how operator[] is usually overloaded:
CMazeSquare& operator[] (const tuple &other)
{
return grid[other.x][other.y];
}
const CMazeSquare& operator[] const (const tuple &other)
{
return grid[other.x][other.y];
}
There a few problems with your code:
First, the definition doesn't match the declaration:
CMazeSquare && operator [] (const tuple &other);
vs
CMaze::CMazeSquare && CMaze::operator [](tuple &other)
Note the const missing in the definition parameters
Then you can't say this[...]. It doesn't do what you think it does.
Lastly why are you trying to return an rvalue reference? You need 2 overloads one for const returning a const lvalue reference and one for mutable returning a mutable reference.
the error you got I suppose is because you don't compile in C++11 and the compiler doesn't understand &&.