jordan@linux-jordan:~> more guess.c

int guess_it_c( int ans, int lower, int higher ) {
    int guess;
    for(;;) {
        guess = (int)((lower + higher)/2);
        if ( ans == guess ) break;
        if ( guess > ans )
            higher = guess -1;
        else
            lower = guess +1;
    }
  return guess;
}

int guess_rec_c( int ans, int lower, int higher ) {
    int guess;
    guess = (int)((lower + higher)/2);
    if (ans == guess) return guess;
    if ( guess > ans ) {
         return guess_rec_c( ans, lower, guess -1 );
    }
    else {
         return guess_rec_c( ans, guess +1, higher );
    }
}

int main() {
    int n;
        
    for (n=0; n<1000000; n++) 
        VERSION(4999,1,10000);
}

jordan@linux-jordan:~> gcc -Wall -DVERSION=guess_it_c -O3 -o guess_it guess.c
jordan@linux-jordan:~> gcc -Wall -DVERSION=guess_rec_c -O3 -o guess_rec guess.c
jordan@linux-jordan:~> time ./guess_it

real    0m0.291s
user    0m0.285s
sys     0m0.003s
jordan@linux-jordan:~> time ./guess_rec

real    0m0.284s
user    0m0.276s
sys     0m0.004s