Problem with rand() in C [duplicate]

Question

Possible Duplicate:
why do i always get the same sequence of random numbers with rand() ?

This is my file so far:

#include <stdio.h>

int main(void) {
    int y;
    y = generateRandomNumber();
    printf("\nThe number is: %d\n", y);
    return 0;
}

int generateRandomNumber(void) {
    int x;
    x = rand();
    return x;
}

My problem is rand() ALWAYS returns 41. I am using gcc on win... not sure what to do here.

EDIT: Using time to generate a random number won't work. It provides me a number (12000ish) and every time I call it is just a little higher (about +3 per second). This isn't the randomness I need. What do I do?

Answer 1

you need to provide it a seed.

From the internet -

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(void)
{
  int i, stime;
  long ltime;

  /* get the current calendar time */
  ltime = time(NULL);
  stime = (unsigned) ltime/2;
  srand(stime);

  for(i=0; i<10; i++) printf("%d ", rand());

  return 0;
}

Answer 2

Standard trick is:

srand(time(0));  // Initialize random number generator.

NOTE: that function is srand, not rand.

Do this once in your main function. After that, only call rand to get numbers.

Depending on the implementation, it can also help to get and discard a few results from rand, to allow the sequence to diverge from the seed value.