Re: Vitual memory problem
On Feb 10, 9:13 pm, "Daniel T." <danie...@earthlink.net> wrote:
Klaib <mom.kl...@gmail.com> wrote:
I am a student doing my project, my program needs a big
arrays size. i used the following functions to create and
delete the pointers, but i have problems based on virtual
memory during the the run time " after 2 or 3 hour", Please
help me to increase cBuilder virtual memory or solving this
problem.
If your program crashes due to starved memory after 2 or 3
hours, then you probably are not deleting your arrays.
You can avoid this problem by wrapping your arrays in classes
and using RAII to make sure the memory is deleted when you are
done with it.
A simple class to start with:
class array3D {
int m, n, i;
std::deque<char> data;
public:
array3D( int m, int n, int i ):
m( m ),
n( n ),
i( i ),
data( m * n * i )
{ }
char at( int x, int y, int z ) const {
// can someone double check my math in the below?
return data[x * n * i + y * i + z];
}
char& at( int m, int n, int i ) {
return data[x * n * i + y * i + z];
}
The usual algorithm is:
return data[ (x*n + y)*i + z ] ;
I think. I'd also throw in an assert:
assert( x < m && y < n && z << this->i ) ;
(I'd also change the names so that I didn't have two i's.)
I'd also either overload operator()(), or overload operator[] to
return proxies which called this function, so that he could use
a more usual syntax. (I prefer the [][][] syntax, but that's
probably because I've used it so much in C.)
};
I use a deque in the above instead of a vector, because the OP is
implying that his data is very large and a deque is less likely to fail
when the memory is fragmented.
On the other hand, it requires globally somewhat more memory.
I'd go with std::vector until I knew fragmentation was the
problem. (Another nice thing about encapsulating everything in
such a class, of course, is that you can easily change the
implementation without any modifications in the client code.)
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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