While Loops

While loops are another way to run a section of code multiple times.

A while loop is similar to a for loop, but it runs indefinitely until a condition is ``.

A while loop looks like this:

while condition:
    # do something

Borrowing from the previous example, let's say we want to print the numbers from 1 to 10.

Here's how it's done using a while loop:

i = 1

while i <= 10:
    print(i)
    i = i + 1

Let's break down how this works:

First, let's define a variable i to keep track of the current number.

i = 1

Then, we want to check if i is less than or equal to 10.

while i <= 10:

If the current value of i is less than 10, then we want to print the current value of i.

    print(i)

Then, we want to increment i by 1. This is very important, otherwise the loop will never end (it will run forever).

    i = i + 1

This is how the loop works:

• Every time the loop finishes running, it goes back to the beginning and checks if the condition is true
• It checks if the condition is true by substituting the current value of i in its place

Infinite loops

Note the last line of the above example. This is one of the dangers of using while loops.

What if we didn't increment i by 1?

Let's say we did this:

i = 1

while i <= 10:
    print(i)

Since i will always be equal to 1, then the condition i <= 10 will always equal 1 <= 10, be equal to true, and the loop will never end.

THIS WILL CRASH YOUR COMPUTER!!!

danger

Always make sure that your while loop has a condition that is false at some point. Otherwise, the loop will run forever (called an infinite loop).

You can usually avoid infinite loops by increasing/decreasing the variable in the condition by 1.

You can do this by using i = i + 1 or i = i - 1.

The shorthand way of doing this is i += 1 or i -= 1.