Question

Somewhere in lines of code, I came across this construct…

//void* v = void* value from an iterator
int i = (int)(long(v))

What possible purpose can this contruct serve?

Why not simply use int(v) instead? Why the cast to long first?

Answer 1

It most possibly silences warnings.

Assuming a 32bit architecture with sizeof(int) < sizeof(long) and sizeof(long) == sizeof(void *) you possibly get a warning if you cast a void * to an int and no warning if you cast a void * to a long as you’re not truncating. You then get a warning assigning a long to an int (possible truncation) which is removed by then explicitly casting from a long to an int.

Without knowing the compiler it’s hard to say, but I’ve certainly seen multi-step casts required to prevent warnings. Why not try converting the construct to what you think it should be and see what the compiler says (of course that only helps you to work out what was in the mind of the original programmer if you’re using the same compiler and same warning level as they were).