I would like to ask how can I retrieve out the list of fibo list and then check whether does the input value by the user is inside the fibo list.
a , b = 1, 1 while num <= sys.maxint: fibo == a , b = b, a+b if num == (b +a+b): print "It is a Fibonacci number" break else: print "It is not a Fibonacci number" break Thank you!
Using a more sophisticated Fibonacci number test, you could use
def is_fibonacci(n): phi = 0.5 + 0.5 * math.sqrt(5.0) a = phi * n return n == 0 or abs(round(a) - a) < 1.0 / n (This is probably the most efficient way to determine whether a number is a Fibonacci number, and it is most probably not the intended solution to your homework. I just included this answer for future reference.)
Possibly a not very efficient solution - using the close formula is more efficient (see Sven's answer), but you can do this:
def fibs(): a,b = 0,1 yield a yield b while True: a,b = b,a+b yield b n = int(raw_input("please, enter a number ")) for fib in fibs(): if n == fib: print "your number is a Fibonacci number!" break if fib > n: print "your number is not a Fibonacci number!" break The fibs generator gives you the list of Fibonacci numbers. You can go through the list, and every number you can check if it's equal to the one the user entered (in which case you're done), or if it's bigger than the one the user entered (and also in this case you're done).
I hope this is useful, at least to understand Python generators.
yield, then you don't get a Python generator, so the for loop does not work. Also, you remove the definition of fibs the code will not work any more. So, answer to your question is "if you remove def or yield the code will no longer work". But why would you want to remove them?x = int(input("Enter a number: ")) A = [0, 1] for i in range(2,720): A.append(A[i-1]+A[i-2]) bool=False for i in range(2,720): if x==A[i]: bool=True break if bool==True: print "Found,Index is:",i+1 else: print "Not Found" 
