Thread: How to generate random numbers the same everytime

Right, so rand() and srand() does something like this (it is not necessarily how it does it in detail, but the PRINCIPLE applies - the actual code may be a bit more complicated):

Code:

static seed = largeNumber0;
int rand()
{
   seed = seed * largenumber1 + largenumber2;
   return seed % MAX_RAND;
}

void srand(int x)
{
   seed = x;
}

So if seed is the same value, then the random numbers will be the same ones every time.
The large numbers are almost always prime numbers or pseudo-primes (that is "nearly primes").

In fact, the SEQUENCE of numbers you get out of rand() will ALWAYS be the same, it's just where in the [hopefully pretty long] sequence you start that will change by modifying the seed.

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Mats