for loop not iterate more than 800000

hi,

i wrote a simple FOR LOOP  program in cocoa-objective c   (MAC os- compiler XCode). but it not working properly. the loop iterating  only upto some value near to 714300( value change each time running). program is given below.

#import <Cocoa/Cocoa.h>

int main(int argc, char *argv[])
{
   unsigned long long i=1;
   
   for(i=1;i!=0;++i)
            printf("%llu\n",i);

      printf("finished");
      //printf("\n%llu",i++);
      
      //printf("\r%llu",i);
      
       return NSApplicationMain(argc,  (const char **) argv);
}


if first printf statement is replaced as printf("%llu-",i); it iterate beyond 1000000 but it run very slowly( take nearly one hour to reach 1000000). what is the problem with this program.