Re: Best way to allocate memory in the constructor
Salvatore Benedetto <salvatore.benedetto@gmail.com> wrote:
Hi,
first of all, thanks to everybody for taking some time and aswering
my question.
Now back to my problem.
I have used char* and int* and my previous email, but that was just an
example. In my constructor, I actually allocate array of structures, or
single structure. I do that with malloc, instead of new(), because there
is not constructor I need to call, and malloc should be faster if I
don't mistake.
Since in my code, speed and low-memory used are a _must_, I wanted to
avoid to use STL components (std::vector,std::auto_ptr, etc..) as they
introduce some overhead, even if little.
Remeber new/delete , new [] delete [] , can be overridden fairly easily
for a 'low level expert' , malloc() and free() are fixed normally.
Further if a compiler's provided operator new()'s use malloc() there
is no difference:)
The amortized cost of std::vector is about 2 pointers per vector,
and if a separate ptr to the begginnge of these arrays is createe
in the ctor of member functions to use there is no added cost beyond
the ctor and no speed loss in ececuting the class's nenber functions,
three ptrs per array, provides easy copying assignment, dtor, automatic
memory management and easy access to the data as if it were created
via malloc, without the pitfalls. Not expensivee probably cheaper
in the long run as maintaince is definitely easier with vector's.:)
three ptrs per array , about 48 or fewer bytes per array , not bad
exchange. How much real data are you storing in 48 bytes???
Don't assume too much, test first:) since using vector is probably
easier, do it first , if it works well enough don't fix it, concentrate
on other problems:)
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