While Loop

The first type of loop we will look at is the while loop. Imagine you want to print numbers 1-10. We would write this using a while loop as follows:

number = 1
while number <= 10: # While number is less than or equal to 10
    print(number) # Print the number
    number = number + 1 # Increase the number by 1

You can see that the while loop has a similar structure to if-else statements.

It works as follows: after the word while comes a condition, which, as long as it holds true, the block of code within the while loop will repeat. As a reminder, a block of code is the indented code following statements like if, else, or while.

Our code will therefore perform the following steps:

1. Set the value of the number variable to 1.
2. Check if number is less than or equal to 10.
3. If yes, print the value of the number variable, increase its value by 1, and go back to step 2.
4. If no, the program ends.

Note that if we forgot to increase number by 1 in our loop, number would always be 1 and our loop would repeat indefinitely. This would cause a non-responsive program that would likely terminate itself after a while. This is always undesirable, so as programmers, we must be careful to avoid this error.