I can't get my Fibonacci sequence program in Python to work

Question

I'm trying to write a program to print the first 100 Fibonacci numbers. This is my code:

def main():

    print("The first 100 Fibonacci numbers are: ")
    fibonacciList = (0,0,1)
    loop = False

    while not loop:

        listLength = len(fibonacciList)
        newFibonacci = fibonacciList[-1] + fibonacciList[-2]
        fibonacciList = newFibonacci + fibonacciList


        if (listLength > 103):
            loop = true

        print(fibonacciList)

main()

When I run it I get the error below referring to the fibonacciList = newFibonacci + fibonacciList line:

TypeError: unsupported operand type(s) for +: 'int' and 'tuple'

I don't understand what's wrong.

P.S.: The two zeroes in the Fibonacci list are there to prevent a few other errors I got earlier.

In line fibonacciList = newFibonacci + fibonacciList, you are performing + over newFibonacci which holds int value and fibonacciList which is a tuple — Moinuddin Quadri
– Moinuddin Quadri, Commented Jan 15, 2017 at 14:37
Adding two zeros to the list isn't the right way to fix whatever problem you have. Only one sequence defined by F(n) = F(n-1) + F(n-2) starts with 2 0s: the infinite list of 0s. — chepner
– chepner, Commented Jan 15, 2017 at 14:38
fibonacciList = (*fibonacciList, newFibonacci) might be closer to what you are looking for — President James K. Polk
– President James K. Polk, Commented Jan 15, 2017 at 14:40

Bob Baxley · Accepted Answer · 2017-01-15 14:54:40Z

1

Try this:

print("The first 100 Fibonacci numbers are: ")
fibonacciList = (0,0,1)
loop = False

while not loop:

    listLength = len(fibonacciList)
    newFibonacci = fibonacciList[-1] + fibonacciList[-2]
    fibonacciList =  fibonacciList + (newFibonacci,)


    if (listLength > 103):
        loop = True

print(fibonacciList)

You can't add an int to a tuple, but you can concatenate two tuples with +, so we can tuple-ize the int with (newFibonacci,).

There are more efficient and readable ways to compute this sequence, but this solves your immediate question.

edited Jan 15, 2017 at 14:54

answered Jan 15, 2017 at 14:42

Bob Baxley

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Shai Aharoni · Accepted Answer · 2017-01-15 14:47:34Z

0

You can try this:

def main():

    print("The first 100 Fibonacci numbers are: ")
    fibonacciList = [0,0,1]
    loop = False

    while not loop:

        listLength = len(fibonacciList)
        newFibonacci = fibonacciList[-1] + fibonacciList[-2]
        fibonacciList.append(newFibonacci)


        if (listLength > 103):
            loop = True
            print(fibonacciList)

main()

answered Jan 15, 2017 at 14:47

Shai Aharoni

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Milo · Accepted Answer · 2017-01-15 15:09:17Z

0

In addition to the other answers you could try the following solution, which is faster, more efficient and better readable:

def fib(n):
    fiblist = []
    x, y = 0, 1

    for i in range(n):
        fiblist.append(x)
        x, y = y, x + y

    print('The first {} Fibonacci numbers are: \n{}'.format(n, fiblist))

Then for the first 100 Fibonacci numbers call the function as follows:

fib(100)

edited Jan 15, 2017 at 15:09

answered Jan 15, 2017 at 14:48

Milo

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