How to align pointer

Question

How do I align a pointer to a 16 byte boundary?

I found this code, not sure if its correct

char* p= malloc(1024);

if ((((unsigned long) p) % 16) !=          


        

Answer 1

posix_memalign is one way: http://pubs.opengroup.org/onlinepubs/009695399/functions/posix_memalign.html as long as your size is a power of two.

The problem with the solution you provide is that you run the risk of writing off the end of your allocated memory. An alternative solution is to alloc the size you want + 16 and to use a similar trick to the one you're doing to get a pointer that is aligned, but still falls within your allocated region. That said, I'd use posix_memalign as a first solution.