Subj : Re: largest memory block
To   : borland.public.cpp.borlandcpp
From : maeder
Date : Thu Mar 24 2005 06:23 pm

"Mohsen" <m_jahanshahi@yahoo.com> writes:

> It is a proplem for an application of mine right now. I have to
> deal with huge arrays say of 1000000 elements or more. Using an
> array of the following type makes the growing process slow:
>
> TArray<TNode> Nodes(100, 0, 100);
>
> Because, the application has to make 9999 reallocations to
> accomodate 1000000 elements. Consider another example:
>
> TArray<TNode> Nodes(100000, 0, 100000);
>
> When reallocating, the occupied memory is 300000, because it
> needs to keep the original array and also allocate a new block
> of 200000 elements to deposit the previous array into it. And
> if it cannot do that the program crashes.

[Assuming you don't know the eventual array size from the beginning,
or you'd initially allocate the right number of elements.]

std::vector is required by the ISO C++ Standard to grow
exponentially. If I understand you right, that would help you both
performance and space wise.

.