How to convert from byte array to word array in c

Question

Using c, I have defined a byte and word as follows:

typedef unsigned char byte;
typedef union {
    byte b[4];
    unsigned long w;
} word;

This allows me to easy go from words to bytes, but I'm not sure of a good way to go the other way. Is it possible to do something like cast from byte* to word* or do I have to stick with iteratively copying bytes to words?

Answer 1

One of the great and terrible things about c is you can take a void pointer and cast it to anything. As long as you know what you are doing it will work, but not something you want to get in the habit of.

Answer 2

const byte input[] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16};
unsigned long output[sizeof(input) / sizeof(unsigned long)];
memcpy(output, input, sizeof(input));