Syntax

About While

While loops allow you to repeat code. In order to repeat code you need to know when the code should start, when it should end and how many steps it must take from start to end. This is an over simplification but it helps when first starting out with loops.

Here is the code from the video –

x = 100
while x>=1:
	print x
	x = x - 1

Key term

Iteration – The process of looping over a section of code. A single loop is known as an iteration.

Helpful links

Some sample code for while loops

Introducing while loops

Kahn academy – while loops (video)

Using boolean variables and while loops (example)

Test your skill

1. Display the numbers from 20 to 30.

x = 20
while x<=30:
    print x
    x = x + 1

2. Display the first 20 square numbers (e.g. 1×1, 2×2,3×3, 4×4….)

x = 1
while x<=20:
    print x * x
    x = x + 1

3. Try the task even stevens on the HackIT website.

x = 1
while x<=20:
    print x
    x = ??????

4. Try the task 99 bottles of beer on the HackIT website.