Runtime Stack allocation

[Adam]

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

void complex_maths_operation(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.

 

[Rolf Magnus]

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

Well, there is the class std::stack, but I doubt that you are referring to
that. However, other than that, C++ doesn't define anything called "stack".

 

[Jeff Schwab]

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

void complex_maths_operation(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]

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

void complex_maths_operation(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.

 

[Adam]

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

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

void complex_maths_operation(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.

 

[Matthias Buelow]

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.