LearnFun Comics#2
The Hundred Hellos
One knight. One hundred guests. One very tired keyboard.
Starring Momo
Python loops · Age 9 and up
Python loops · Age 9 and up
The Hundred Hellos: Python loops comic
Robot Castle
Sir Oops-a-Lot: I must greet 100 guests. I shall type it 100 times!
print("Hello")
print("Hello")
print("Hello")Momo: Stop! Computers love repeating. Use a loop!
Meet the for loop
for i in range(3):
print("Hello")Hello Hello Hello
Momo: Line one says: do this 3 times. The spaces before print show which line repeats.
Sir Oops-a-Lot: But what is this i? I have only a saucepan.
for i in range(3):
print(i)0 1 2
Momo: i is a counter. range(3) starts at 0 and stops before 3.
Your turn, hero!
Sir Oops-a-Lot♥♥♥
for i in range(2):
print("Hi")How many times does this print Hi?
2. range(2) counts 0 and 1. That is 2 times.
for i in range(3)
print("Hello")SyntaxError: expected ':'
Momo: Two bugs! The first line needs a colon. The next line needs its spaces.
He tries something new
Sir Oops-a-Lot♥♥♥
for i in range(1, 4):
print(i)What does this print?
1 2 3. range(1, 4) starts at 1 and stops before 4.
The final battle
Sir Oops-a-Lot♥♥♥
total = 0
for i in range(1, 4):
total = total + i
print(total)What number comes out?
6. 0 + 1 = 1, then 1 + 2 = 3, then 3 + 3 = 6.
Two lines. One hundred guests.
for i in range(100):
print("Hello, guest")Sir Oops-a-Lot: My saucepan salutes you!
Momo: Now try it yourself!
The End?
Villain card won! Answer again in a few days and it turns gold.
Remember
- A for loop repeats the lines with spaces in front.
- range(3) gives 0, 1, 2: it stops before 3.
- The first line ends in a colon.
Next morning a new order arrives: every guest wants a different greeting. His saucepan starts to shake...
A comic book about Python for loops. Learn how range counts, spot the two commonest bugs and save a robot knight from a lot of typing.