203: Mainline

You can even, if you want, bring the reassignment of the result variable within the reassignment part of the for loop, joining it to the reassignment of the counter variable. The result is a for loop with an empty embedded statement, which, as you may recall from Segment 166, consists of a semicolon only:

int power_of_2 (int n) { 
  int counter, result; 
  for (counter = n, result = 1;         /* Initialization  */ 
       counter;                         /* Test            */ 
       --counter, result = result * 2)  /* Reassignment    */ 
    ;                                   /* Empty statement */ 
  return result; 
}