RosettaCodeData/Task/Fibonacci-sequence/C/fibonacci-sequence-2.c

long long int fibb(int n) {
   int fnow = 0, fnext = 1, tempf;
   while(--n>0){
      tempf = fnow + fnext;
      fnow = fnext;
      fnext = tempf;
      }
      return fnext;
}