math.rand

from "math" import rand

Returns a random integer in range 0..RAND_MAX

Return value

An integer in the closed range 0 to math.RAND_MAX.

Notes

The generator is a linear congruential one over a 32-bit seed held in the shared state. Its arithmetic wraps at 32 bits, so the same seed gives the same sequence of results on every platform and every build.

The seed starts randomized when the process starts, so a rand() call with no prior srand call is not reproducible. Call srand with a fixed seed first when a script needs the same numbers on every run.

The seed lives in the shared state, one per VM rather than one per module, so a seed set from any module changes what every module's rand() returns next.

Example

from "math" import rand, srand, RAND_MAX

// seed first: an unseeded rand() is not reproducible, so examples always seed
srand(1)

println("rand() =", rand())
println("rand() =", rand())
println("rand() =", rand())

// every draw stays within the documented range
let r = rand()
println("r >= 0 && r <= RAND_MAX =", r >= 0 && r <= RAND_MAX)

rand() = 1015571940
rand() = 1586027347
rand() = 18251880
r >= 0 && r <= RAND_MAX = true

See also