Question

ive seen functions passing pointers in their parameters and they are common in dynamic use executing different functions after afew steps. However i came across this representation in a header file:

void *allocate_mem(u_int32_t n);

Any clue to how it is to be used? Is the function a pointer or does it return a pointer?

Answer 1

See my comments.

Please use cdecl.org whenever you have questions like this… entering void *allocate_mem(u_int32_t), we get the following.

declare allocate_mem as function (u_int32_t) returning pointer to void.

So, we know allocate_mem returns void *. Now, you’re probably wondering why you would ever want a pointer to void…

§6.3.2.3.1 of the C99 standard states as follows.

A pointer to void may be converted to or from a pointer to any incomplete or object type. A pointer to any incomplete or object type may be converted to a pointer to void and back again; the result shall compare equal to the original pointer.

Thus you can convert the result of allocate_mem to fit your needs, e.g.

float *data = allocate_mem(1024 * sizeof(float))