I'm reading bytes from a buffer. But sometimes what I'm reading is a word or longer.
// assume buffer is of type unsigned char *
read_ptr(buffer+(position++))
That's fine but how can I post-increment position by 2 or 4? There's no way I can get the += operator to post-increment, is there?
Reason is, I have this big awful expression which I want to evaluate, while at the same time incrementing the position variable.
I think I came up with my own solution. I'm pretty sure it works. Everyone's gonna hate it though, since this isn't very readable code.
read_ptr(buffer+(position+=4)-4)
I will then make this into a macro after testing it a bit to make sure it's doing the right thing.
IN CONCLUSION:
Don't do this. It's just a bad idea because this is the sort of thing that generates unmaintainable code. But... it does turn out to be quite easy to convert any pre-incrementing operator into a post-incrementing one.
Well, I did answer my question in the edit... Basically what I wanted was a single expression which evaluates to the original value but has a side effect of incrementing by an arbitrary amount. Here are some macros.
#define INC(x,inc) (((x)+=(inc))-(inc))
#define INC2(x) INC(x,2)
#define INC4(x) INC(x,4)
#define INC8(x) INC(x,8)