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well, if by random you mean pseudo-random then yes using rand() would be the way to go. But, as there is no truly random number (other than maybe radioactive decay), it depends on how random you want it. I recommend you at least seed rand with say an integer from /dev/random or /dev/urandom.

Yes, on your system, with your word length, and a number of other nonportable assumptions, as well as using the modulo operator to select a subrange, a classic beginner's error.

well yours returns a floating point for no reason.
that also means it has to do a (potentially slow)floating point to integer conversion.

Yes, and most uses for rand() in modern times require a float or a double. There is an equivalent integer version, but it doesn't see much use these days.

There *is* a way to get a decent random number out of rand() only using integer ops, but it's painful.

1. Figure out the number of bits B in the next highest power of two of (max - min). If (max -min) happens to already be a power of two, that's nice.
2. Figure out how many meaningful bits rand() can produce. That's relatively easy by counting how many times you have to unsigned right shift to make RAND_MAX zero. Be careful you don't count too many or else entropy goes through the floor.
3. Extract the top B meaningful bits from the rand() call.
4. If that produced a number less than (max - min) you're done. If not, call rand() again until you get a number less than (max - min).

This, of course, assumes that (max - min) < RAND_MAX.

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