Form 4 - Computer
2024-2025
Floor 4 - Computer Room
Mr. Peter
While Loop & List
Santa Rosa de Lima English Secondary School
聖羅撒英文中學
Colégio de Santa Rosa de Lima - Secção Inglesa
Outline
List
1.
Explore the concept of List
How to process List in While Loop
2.
Focusing on the List processing in looping
Python List implementation
3.
Define while loop statement for List scanning
What is List?
List is a list of variables
What is List?
What is List?
box
1
This is a variable containing number 1
What is List?
box
1
List is a list of variables
box
1
box
1
box
1
box
1
...
[
]
What is List?
box
1
List is a list of variables
box
1
box
1
box
1
box
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
box
1
box
1
box
1
box
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
1
1
box
1
box
1
box
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
1
1
box
1
box
1
2
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
1
1
box
1
3
1
2
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
1
1
4
1
3
1
2
1
...
[
]
Each variable inside the List uses position index as variable name
What is List?
List is a list of variables
We can assign a name for this list
0
1
...
[
]
2
1
4
1
1
1
3
1
Each variable inside the List uses position index as variable name
What is List?
0
1
List is a list of variables
...
[
]
2
1
4
1
1
1
3
1
We can assign a name for this list
boxes =
Each variable inside the List uses position index as variable name
What is List?
0
1
...
[
]
2
1
4
1
1
1
3
1
boxes =
In Python:
boxes = [ 1, 1, 1, 1, 1 ]What is List?
0
1
...
[
]
2
1
4
1
1
1
3
1
boxes =
In Python:
boxes = [ 1, 1, 1, 1, 1 ]print( boxes[ 0 ] )Get variable from List
list[ position ]
Output: 1
What is List?
0
a
"
"
2
c
4
e
1
b
3
d
text =
What is List?
0
a
"
"
2
c
4
e
1
b
3
d
text =
We can also get letter from text
What is List?
0
a
"
"
2
c
4
e
1
b
3
d
text =
We can also get letter from text
text = "abcde"What is List?
0
a
"
"
2
c
4
e
1
b
3
d
text =
We can also get letter from text
text = "abcde"Get letter from text
text[ position ]
What is List?
0
a
"
"
2
c
4
e
1
b
3
d
text =
We can also get letter from text
text = "abcde"print( text[ 0 ] )Get letter from text
Output: a
text[ position ]
Python List Exercises
Python List - Ex01
Write a Python program using a while loop to print each letter from a text "abcdefghijklmnopqrstuvwxyz".
1.
Use a while loop to iterate through the numbers.
1
Print each letter from the letters
2
letters = "abcdefghijklmnopqrstuvwxyz"a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
Expected output:
( The variable "i" increases from 0 to 25 )
Save your file as "ClassNumber_YourName_Ex01.py"
Python List - Ex02
Write a Python program that calculates the sum of digits.
2.
Use a while loop to iterate through the numbers.
1
Print the accumulated result
2
digits = "78435683769834734829347239857298561024"Sum of all digits: 199Expected output:
( The variable "i" increases from 0 to len(digits) )
Save your file as "ClassNumber_YourName_Ex02.py"
Python List - Ex03
Write a Python program that reverses the string "ILovePython" using a while loop and prints the result.
3.
Use a while loop to iterate through each charater.
1
Accumulate them to be one string
2
text = "ILovePython"( The variable "i" decreases from 11 to 0, with syntax: s[ i ] )
Save your file as "ClassNumber_YourName_Ex03.py"
nohtyPevoLI