What's the difference between arc4random and random?

Question

What\'s the difference between arc4random and random?

Answer 1

random is known to be predictable and thus not to be used for secure pseudo-random number generation. arc4random is a newer, less predictable pseudo-random number generator. If you are not using it for anything secure, random will work fine.

Answer 2

Depending on your system, random() may or may not be the old, reliable, and predictable UNIX random(). On modern FreeBSD systems, and Linux 2.6 systems that have the /dev/random device, the default random() implementation reads from /dev/random until it is exhausted. This is likely to produce somewhat better random numbers than any numerical sequence generator, depending on the sources of randomness you've stirred into /dev/random.

Consulting the documentation (man pages, etc) for the system you are deploying the program on is highly suggested.