Lesson 4 👉 while loops

Do Now

# what do you think this will do?
n=1
while n>0:
  print n
  n = n+1

bad stuff infinite loop! ¹

✍ while Loop

Code that repeats while a condition is true.

x=1
while x in range(0,4):
  print x
  x = x+1

Let’s take a closer look:

n=1 # sets n to 1. What happens if we don't?
while n>0:
 print n
 n = n+1
# Predict!
while True:
  print "whoa"
# What about this? What gives?
while x<5:
  print x
  x = x + 1

Countdown v2.0

Write a program called countdownV2.py

It takes any number as input, starts counting down and ends with a BOOM! (or similar exclamation.)

It should look like this:

Enter number: 10
10
9
8
7
6
5
4
3
2
1
BOOM!