operator [][] overloading 1

[maur3r]

I wrote a class "matrix" which uses **double. I am trying to write an operator [][] for this class to be able to perform f.ex

matrix A;
A[1][1]=2;

Does anybody know how to overload such operator?

Regards, Martin

(OS and comp.)
using Linux and gcc

 

[Salem]

You have to overload it in two steps, each returning a different type.

One of the [ ] returns A[ row ]

The other one takes the result of A[ row ] overload and returns (first result)[ col ], which is your actual data.

http://www.parashift.com/c++-faq-lite/operator-overloading.html#faq-13.10

Has some alternative thoughts on the matter.


--

 

[maur3r]

I don't quite follow the presented option. Would you mind giving a simple example? I would very much appreciate.

Regards, Martin

(OS and comp.)
using Linux and gcc

 

[cpjust]

I think the option in that link is much easier and cleaner. You'd basically reference your matrix like this:

Matrix matrix( numRows, numCols );
...
value = matrix( row, col );

 

[maur3r]

Yes but unfortunately I have to create my project compatible with an interface where indexing operator is declared in the way [rows][cols]

Regards, Martin

(OS and comp.)
using Linux and gcc

 

[chipperMDW]

Salem is saying that something that does this:

Matrix A;
A[1][1] = 2;

is going to be equivalent to something like this:

Matrix A;
Matrix::Row row = A[1];
row[1] = 2;

There's no such thing as an [tt]operator[][][/tt]. You have to have two implementations of [tt]operator[][/tt]: one that is applied to a matrix and returns a row, and one that is applied to a row and returns an element. Your desired syntax just uses them both in a single step.