Algorithm function for fibonacci series [closed]

Answer 1

I interpret the question differently....given a number as an input, what is the index of that number in the series? e.g. input=5, then index is 5 (given the sequence is 0 1 1 2 3 5 where the index begins with 0)

This the code is as follows (which returns the index) [Disclaimer: Adapted from the code given at http://talkbinary.com/programming/c/fibonacci-in-c/ ]

int Fibonacci(int n)
{
  if ( n == 0 )
    return 0;
  if ( n== 1 )
    return 1;

  int fib1 = 0; 
  int fib2 = 1;
  int fib = 0;
  int i = 0;

for (i = 2; ; i++ ) 
{

    fib = fib1 + fib2;
    if ( n == fib )
       break;
    fib1 = fib2;
    fib2 = fib;
}


  return i;
}