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?
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 =
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
Check if a List is Sorted in Ascending Order
1.
numbers = [1, 4, 6, 9, 13, 14, 17, 21, 26, 31, 34, 39, 43, 47, 50, 54, 59, 63, 67, 72, 76, 81, 85, 90, 93, 97, 100]Save your file as "ClassNumber_YourName_Ex01.py"
Write a Python program to check if a given list is sorted in ascending order or not. If the list is sorted, print "The list is sorted", otherwise print "The list is not sorted".
Check if the current number is greater than the previous one.
2
Print "The list is sorted", if sorted, otherwise print "The list is not sorted".
3
Use a while loop to iterate through the numbers.
1
( The variable "i" increases from 0 to len(numbers) )
Python List - Ex02
Check if a List is a Palindrome
1.
numbers = [1, 2, 3, 4, 5, 4, 3, 2, 1]Write a Python program to check if a given list is a palindrome or not. A palindrome list reads the same backward as forward. If the list is a palindrome, print "The list is a palindrome", otherwise print "The list is not a palindrome".
If any pair of elements differ, set a flag to indicate the list is not a palindrome and exit the loop.
2
Finally, print whether the list is a palindrome based on the flag's value.
3
Use two pointers to compare elements from the start and end of the list, moving towards the center.
1
Save your file as "ClassNumber_YourName_Ex02.py"
Python List - Ex03
Extracting Positive Numbers from a List
1.
numbers = [-5, 0, 12, -8, 3, 0, 7]Write a Python program that takes a list of numbers (both positive and negative, including zero) and extracts all the positive numbers (excluding zero) from the list. Use a while loop and the append() method to achieve this.
2
3
Use a while loop to iterate through the numbers.
1
( The variable "i" increases from 0 to len(numbers) )
Append only the positive numbers (greater than 0) to a new list.
Print the final list containing all the positive numbers.
Save your file as "ClassNumber_YourName_Ex03.py"
[12, 3, 7]