c++ - Will rand() sometimes return the same consecutively? -

i'm curious, can single-threaded program ever same return value 2 consecutive calls rand()?

so, assertion ever fire?

assert(rand() != rand()); 

if can find 1 example does, answer question "yes".

#include <stdio.h> #include <stdlib.h>  int main(int argc, char* argv[]) {   unsigned int i;   for(i = 0; ; i++) {     int r = rand();     if (r == rand()) {         printf("oops. rand() = %d; = %d\n", r, i);         break;     }   }   return 0; } 

prints oops. rand() = 3482; = 32187 on windows visual studio 2010.

edit: use version below detect sequences 2 consecutive rand() calls return same value. c specifies rand() should return "pseudo-random integers in range 0 rand_max" , rand_max should @ least 32767. there no constraints on quality of prng, or it's implementation, or other details such whether 2 consecutive rand() calls can return same value.

#include <stdio.h> #include <stdlib.h>  int main(int argc, char* argv[]) {   unsigned int i;   int r1 = rand();   int r2 = rand();   for(i = 0; ; i++) {     if (r1 == r2) {         printf("oops. rand() = %d; = %d\n", r1, i);     }     r1 = r2;     r2 = rand();   }   return 0; }