API fastrandom

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Returns a random number within the specified interval.

rand = fastrandom([ [low, ] high])


Number - lower integer limit on the returned random value.
Number - upper integer limit on the returned random value.


Number - Generated random value. If no arguments were specified, the value is a uniformly-distributed decimal between 0 (inclusive) and 1 (exclusive). Otherwise, returns a uniformly-distributed integer between low (1 if not specified) and high, both bounds inclusive.


  • This function uses C's rand function as a random number generator. On the Windows client, the implementation of random(high) is equivalent to the following, which is not cryptographically secure: it is possible to derive its internal state from a few samples of its output and correctly predict the results of subsequent calls.
local state = 0 -- initialized by seeding
function random(high)
 state = (state * 214013 + 2531011) % 2^32;
 local rand = math.floor(state / 2^16) % 2^15;
 return 1 + math.floor(rand / 0x7fff * high)
  • Lua's math.randomseed is not available in World of Warcraft; the random number generator is instead seeded by the client at startup.

See also

Patch changes

Mists of Pandaria Patch 5.4.2 (2013-12-10): Name changed to fastrandom; random and math.random now use a different RNG algorithm.