Python Program to Print Fibonacci Numbers using While Loop

In this tutorial, we are going to print Fibonacci numbers until a given number by using a while loop in Python.

This program generates all the Fibonacci numbers up to a given number n using a while loop.

Simple Code:

n = int(input("Enter a number: "))

a = 0
b = 1

while a <= n:
    print(a)
    a = b
    b = a + b

Output:

Enter a number: 57
0
1
2
4
8
16
32

Code with Comments:

# Here we take Input from user
n = int(input("Enter a number: "))

# Initialize variables
a = 0
b = 1

# Loop until a is less than or equal to n
while a <= n:
    # Print the current Fibonacci number
    print(a)
    # Update a and b to generate the next Fibonacci number
    a = b
    b = a + b

Explanation:

We start by getting the input from the user by using input function, which is the upper limit n.

Then, we initialize two variables a and b to 0 and 1, respectively.

These variables will keep track of the current and next Fibonacci numbers in the sequence.

We use a while loop to repeatedly check whether a is less than or equal to n.

If it is, we print the current Fibonacci number using the variable a, and then update the variables a and b to generate the next Fibonacci number in the sequence.

The update is done using the expression a = b and b = a + b which first sets a to b (i.e., the next Fibonacci number) and then sets b to a + b (i.e., the sum of the current and next Fibonacci numbers).

This process continues until the current Fibonacci number a is greater than n, at which point the