> On Mar 3, 2015, at 12:47 AM, Patrick J. Collins
> <[email protected]> wrote:
>
> but if I change
> float coefficients[11];
> to:
> float *coefficients;
> That warning goes away, but I don't understand why that would be acceptable..
It’s not. ‘coefficients’ is now an uninitialized pointer, i.e. it contains
garbage, and reading or writing it is very likely to crash. The compiler ought
to be warning you about this; maybe your target settings don’t have the
uninitialized-variable warning enabled?
A pointer just points to something; it isn’t responsible for allocating memory
for that something. By declaring the array as “float coefficients[11]” you did
tell the compiler to allocate space for 11 items on the stack, but of course
you can’t return a pointer to that.
You could modify the method to initialize the pointer by malloc’ing a buffer.
Then the caller of the method becomes responsible for freeing the buffer, which
is annoying.
The other option, which I believe is the most frequently used in practice, is
to make the buffer pointer an input parameter rather than a return value. So
the caller is responsible for finding space for the array, and passes it to the
-coefficientsFor: method, which fills in the array. It would look something like
+ (void) getCoefficients: (float*)outCoefficients forBuffer:
(Buffer*)buffer;
—Jens _______________________________________________
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