The ANSI C rand() doesn't actually specify any particular algorithm. The complete set of requirements for rand() is just that: rand() computes a sequence of ps

The ANSI C rand() doesn't actually specify any particular algorithm. The complete set of requirements for rand() is just that: rand() computes a sequence of pseudo-random integers in the range 0 to RAND_MAX; RAND_MAX must be at least 32767; if srand() is called with the same seed value, the same sequence of values will be produced; calling rand() before calling srand() acts as if srand() had been called with a seed of 1; and no library function can peturb the pseudo-random sequence. Historical C standard library implementations did tend to use the same or similar LCRNGs, but that was never a requirement, and is no longer the case.