Python Strings and Character Encoding

Python Strings and
Character Encoding

CSC501-Term 3
AQB ATHS 2022-2023

We'll be covering the following objectives:

PC2.1

Understand how characters are coded and stored in the computer's memory and recognize the main
encoding terms such as ASCII, Unicode, and codepoint.

PC2.2

Understand Strings as immutable sequence and write code to perform simple operations as concatenate +,
replicate *, ord(), chr(), indexing, slice, in , not in…etc

PC2.3

Differentiate between Strings and List in Python as immutable and mutable sequence.

PC2.4

Create simple program to use the main Python built-in functions such as min(), max(), list(), index(), count(),

PC2.5

Practice the standard Python strings’ methods capitalize(), center(), endswith(), find(), isalnum(),
isalpha()…etc

PC2.6

Write codes to sort String using sorted() & sort() functions , and compare Strings using logical operators.

PC2.7

Create programs that have the structure of accepting the user’s string input, process , then providing
expected output

Understanding Character Encoding

• In computers, characters are represented using bits.
• For example, the letter 'A' is represented as 01000001 in binary.
• There are several encoding schemes used to represent characters,

such as ASCII, Unicode, and codepoint.

• ASCII is a standard encoding scheme that represents characters using

7 bits.

Fill in the Blank

In computers, characters are represented using ____.

Drag and Drop

• For example, the letter 'A' is represented as 01000001 in ​

Placeholder

. • There are several ​

Placeholder

schemes used to represent ​

Placeholder

,

Drag these tiles and drop them in the correct blank above

binary

encoding

characters

Understanding
Character
Encoding

• ASCII stands for "American Standard Code

for Information Interchange".

• Unicode is a more advanced encoding

scheme that supports characters from
different languages and scripts and uses up
to 32 bits to represent a character.

• Codepoint is a unique identifier for each

character in Unicode.

• Understanding character encoding is

important for working with text data in
Python.

ASCII Sample

ASCII Vs Unicode

Drag and Drop

•ASCII stands for "​

Placeholder

​

Placeholder

​

Placeholder

for ​

Placeholder

​

Placeholder

".•U

Drag these tiles and drop them in the correct blank above

American

Standard

Code

Information

Interchange

Drag and Drop

​

Placeholder

is a more advanced ​

Placeholder

scheme that supports ​

Placeholder

from different ​

Placeholder

and scripts and uses up to ​

Placeholder

to represent a character.

Drag these tiles and drop them in the correct blank above

Unicode

encoding

characters

languages

32 bits

Working with Strings

• A string is a sequence of characters enclosed in quotes.

• Strings are immutable in Python, which means they

cannot be changed directly.

• You can perform several operations on strings, such as

concatenation (+), replication (*), ord() (to get the ASCII
value of a character), chr() (to get the character for an
ASCII value), indexing (to access individual characters in
a string), slicing (to extract a substring from a string), in
(to check if a substring is present in a string), and not in
(to check if a substring is not present in a string).

• Knowing how to work with strings is essential for

processing text data in Python.

Match

Match the following

• String is

• Strings are

• concatenation (+), replication (*), ord()), chr(),slicing()

• chr()

• indexing

a sequence of characters enclosed in quotes

immutable in Python

are operations on strings

to get the character for an ASCII value

to access individual characters in a string

• a sequence of characters enclosed in quotes

• immutable in Python

• are operations on strings

• to get the character for an ASCII value

• to access individual characters in a string

Samples:

Difference between Strings and Lists

• A list is a collection of items that can be of different types.
• Lists are mutable in Python, which means they can be changed

directly.

• The main difference between strings and lists is their mutability.
• You can perform several operations on lists, such as adding and

removing items, accessing individual items, and sorting the list.

• Understanding the difference between strings and lists is important

for choosing the appropriate data structure for your program.

Activity showing the difference
between String and list

• This code demonstrates the difference

between strings and lists in Python.

• The first section shows that strings are

immutable.

• The second section shows that lists are

mutable.

• The third section shows that strings

have some methods that lists don't
have, such as the split() method, which
splits a string into a list of substrings.

• The fourth section shows that lists have

some methods that strings don't have,
such as the append() method, which
adds an element to the end of a list.

Using Built-in Python Functions

• Python provides several built-in functions that you can use to process

strings and lists.

• Some of the main functions for lists include min(), max(), list(),

index(), and count().

• These functions can be used to perform common operations on lists,

such as finding the minimum and maximum values, converting a
string to a list, finding the index of an item, and counting the number
of occurrences of an item.

• You can use these functions in your programs to save time and effort.

• This code demonstrates how

to use the main built-in
functions in Python for lists.

• The first section shows how to

use the min() and max()
functions to find the minimum
and maximum values in a list.

• The second section shows

how to use the list() function
to convert a string to a list.

• The third section shows how

to use the index() function to
find the index of an item in a
list.

• The fourth section shows how

to use the count() function to
count the number of
occurrences of an item in a
list.

Practice Python String Methods

• Python provides several built-in methods that you can use to process

strings.

• Some of the main string methods include capitalize(), center(),

endswith(), find(), isalnum(), isalpha(), and many more.

• These methods can be used to perform common operations on

strings, such as capitalizing the first letter, centering the string,
checking if the string ends with a certain substring, checking if the
string is alphanumeric or alphabetic, and many more.

• You can use these methods in your programs to manipulate strings

easily and efficiently.

Examples:

Sorting Strings and Comparing Strings

• Python provides two functions for sorting

strings: sorted() and sort().

• sorted() returns a new sorted list of

characters from the original string, while
sort() sorts the original string in-place.

• You can also use logical operators to

compare strings, such as ==, !=, <, <=, >, and
>=.

• Understanding how to sort and compare

strings is important for processing text data
and performing string operations in Python.

Examples:

Accepting User Input and
Providing Output

• Python provides several built-in functions

for accepting user input and providing
output.

• The input() function can be used to accept

user input as a string, which can then be
processed in your program.

• The print() function can be used to provide

output to the user, such as the results of
string operations or program output.

• You can create programs that accept user

input, process it, and provide the expected
output using these functions.

Example:

Conclusion

• In this lesson, we covered several objectives related to working with strings

and character encoding in Python.

• We learned about character encoding schemes such as ASCII, Unicode, and

codepoint, and how to work with strings as immutable sequences using
various operations and methods.

• We also learned about the difference between strings and lists, and how to

use built-in Python functions to process them.

• Finally, we learned how to accept user input and provide output using

input() and print() functions.

• With these skills, you can start creating Python programs that work with

text data and manipulate strings efficiently and effectively.