iPhone: random() function gives me the same random number everytime

Question

I am using function random()%x for the generation of a random number, but every time I start the application I see that it creates or generates the same number.

Lik

Answer 1

For newbies that come across this post:

The random() function produces a pseudo-random sequence. random() ways gives you the same pseudo-random sequence each time you use it. You need to "seed" the sequence to pick a different starting point so each time you run it so it appears different. You can use the system time to seed (srandom(time(NULL)) or use the helper function srandomdev().

To experiment try:

#include "stdio.h"

int main(void) {
    int i;
    for (i = 0; i < 10; i++)
        printf("%d\n", random());

    return 0;
}

You'll always get the same sequence, on my computer it gives:

1804289383
846930886
1681692777
1714636915
1957747793
424238335
719885386
1649760492
596516649
1189641421

More reading:

• The random man page for more information. (Run man random from Terminal.)