Runtime Stack allocation

[Adam]

Is there a way in C++ to allocate a variable amount of stack space at
run-time?

void complex_maths_o peration(const int num_rows, double* vector)
{
double temp[num_rows];
....
}

The obvious answer is to use the heap... but if this isn't an option.

[Jeff Schwab]

Re: Runtime Stack allocation

Adam wrote:

Is there a way in C++ to allocate a variable amount of stack space at
run-time?
>
void complex_maths_o peration(const int num_rows, double* vector)
{
double temp[num_rows];
....
}
>
The obvious answer is to use the heap... but if this isn't an option.

Recurse. Your base case can depend on a run-time variable.

[Andrey Tarasevich]

Re: Runtime Stack allocation

Adam wrote:

Is there a way in C++ to allocate a variable amount of stack space at
run-time?
>
void complex_maths_o peration(const int num_rows, double* vector)
{
double temp[num_rows];
....
}
>
The obvious answer is to use the heap... but if this isn't an option.
...

There's no C++-standard way to do that.

If you don't mind going outside the limits of C++ standard, look up the 'alloca'
function. It does exactly what you want but has some limitations, which might be
(or might not be) critical in your case.

--
Best regards,
Andrey Tarasevich

[Adam]

Re: Runtime Stack allocation

Thanks Andrey,

Yes, 'alloca' style allocation is what I was looking for.
This sort of behavor is supported by Ada and I've become fond of it.

Adam

"Andrey Tarasevich" <andreytarasevi ch@hotmail.comw rote in message
news:OPqdnWZLEK axhFzanZ2dnUVZ_ ubinZ2d@comcast .com...

Adam wrote:

>Is there a way in C++ to allocate a variable amount of stack space at
>run-time?
>>
>void complex_maths_o peration(const int num_rows, double* vector)
>{
> double temp[num_rows];
> ....
>}
>>
>The obvious answer is to use the heap... but if this isn't an option.
>...

>
There's no C++-standard way to do that.
>
If you don't mind going outside the limits of C++ standard, look up the
'alloca' function. It does exactly what you want but has some limitations,
which might be (or might not be) critical in your case.
>
--
Best regards,
Andrey Tarasevich

[Matthias Buelow]

Re: Runtime Stack allocation

Adam wrote:

Yes, 'alloca' style allocation is what I was looking for.
This sort of behavor is supported by Ada and I've become fond of it.

Don't allocate too much with alloca(), on most systems, there's a lot
less stack space than heap space available with default settings.