How do I overload [] operator such that......
Author
Hi, I''m writing a generic matrix implementation for an artificial neural network. I want to overload the subscript operator [], such that I can write:
Matrix [j] = Value;
or
Value = Matrix [j];
I know I can overload [], but how does one go about overloading [][] or even [][][]!???
Thanks for any help you can give. </i>
You make that operator[] return a row (or column) to that matrix. That row is also an object, which has overloaded []. Then the second [] will access the row''s overloaded [].
I think it goes like this:
matrix[n][m] == (matrix.operator[](n)).operator[](m)
So the matrix.operator[](n) must return an object for which [] is overloaded.. Eh, I don''t think I''m going to say it third time
I think it goes like this:
matrix[n][m] == (matrix.operator[](n)).operator[](m)
So the matrix.operator[](n) must return an object for which [] is overloaded.. Eh, I don''t think I''m going to say it third time
[] will have to return some object that can have [] called on it.
mtl is a generic matrix library
boost has got some new stuff in it for BLAS
mtl is a generic matrix library
boost has got some new stuff in it for BLAS
Author
Oh - thanks mate - I think what I really wanted was the MTL - so much easier to use this than have to write my own.
Thanks a lot for your help.
Or use operator():
HTH, Steve
Steve
DirectX Programmer
Soon to be the new Bill Gates
float Matrix::operator() (int nRow, int nCol){ return m_fMat[nRow][nCol];}Matrix m;float f;f = m(1,2); HTH, Steve
Steve
DirectX Programmer
Soon to be the new Bill Gates
Using programming tricks to get a nice looking [][] operator is the height of stupid. Is the extra inefficiency and complexity introduced really worth not using the () operator?
If you want syntactic sugar, use Perl or something. In C++, it very often leads to bad, bad, bad code.
Don''t listen to me. I''ve had too much coffee.
If you want syntactic sugar, use Perl or something. In C++, it very often leads to bad, bad, bad code.
Don''t listen to me. I''ve had too much coffee.
You could just overload [] in the matrix class, and then overload the comma operator in some helper class to get Matrix[2,3,4]. Heh, finally a reason to use operator comma.
quote:Original post by Brobanx
You could just overload [] in the matrix class, and then overload the comma operator in some helper class to get Matrix[2,3,4]. Heh, finally a reason to use operator comma.
Pointless. Inconsistent. Violates intentionality (what does that syntax convey to the reader of the code, uninformed of your overload but familiar with C++?)
Just use operator (). It''s quick, efficient and conveys intent quite well (function object-like syntax).
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