Variables:

What is a Variable:

In Python, a variable is a symbolic name that is used to reference a value stored in the computer's memory. It acts as a label for the data, allowing you to access and manipulate the value without needing to know its exact memory location. Variables make it easier to write and read code by using descriptive names to represent data 

Dynamic Typing:

Python is a dynamically-typed language, which means you do not need to specify the type of the variable when you create it. The type is inferred from the value assigned to it. For example: 

Rules for Variables:

• • Can contain letters, numbers, and underscores

  • Can Start with an underscore

  • Spaces Not Allowed

  • AVOID KEYWORDS

  • Variable Names = short, descriptive

Preference: Camel or Snake??

• • Camel Case

    • • In camel case, the first word is lowercase, and each subsequent word starts with an uppercase letter.

        • • Example: myVariableName, userInput, totalScore

      • Camel case is often used in Java or other languages but is not the standard convention in Python.

  • Snake Case

    • In snake case, all letters are lowercase, and words are separated by underscores (_).

      • • Example: my_variable_name, user_input, total_score

    • Snake case is the preferred convention for variable names in Python

      • • Recommended by the PEP 8 style guide. 

        • Python developers commonly use this style to maintain readability and consistency

Which is Better?

• • You picking variables names is really important for the readability of your code.

  • Let's Take a look at some examples for you to decide:

    • • The number of pages in a book:

        • • • • pages or number_of_pages_in_book

      • The average grade of a student:

        • • • average_grade or student_grades_average

      • The username for logging in:

        • • • username or user_login_name

      • The number of items in a shopping cart:

        • • • cart_items or number_of_cart_items

      • The name of a movie:

        • • • movie_title or title_of_movie_being_watched

      • The distance between two cities:

        • • • distance_between_cities or city_distance_in_km

      • The result of a math calculation:

        • • • result or calculation_output_value

      • A flag to check if the user is logged in:

        • • • is_logged_in or logged_in_status_boolean

      • The total cost of a purchase:

        • • • total_cost or sum_of_all_purchase_amounts

      • The last item in a list:

        • • • last_item or final_list_element

Variables Are Labels

• Variables are often described as boxes you can store values in. This idea can be helpful the first few times you use a variable, but it isn’t an accurate way to describe how variables are represented internally in Python. 

• It’s much better to think of variables as labels that you can assign to values. 

• You can also say that a variable references a certain value.

NEED TO KNOW THIS FIRST

To perform a basic print, you can do the following (TRY THESE):

count = 10

print("The Current Count is: ", count)

myvar = "Python"

print("I Like ", myvar, " because it is cool")

Task 1: Find 10 Keywords in Python

• Research and List 10 RESERVED or KEYWORDS in Python which you CAN NOT NAME VARIABLES

• Complete the Google Form

Task 2: Create 10 Variable Names

• Create 10 Variables which follow:

  • 5 Must be Snake Case

  • 5 Must be Camel Case

  • All must follow naming conventions

Task 3: Variable Tasks - GOOGLE FORM

• Complete the following Google Form

• You must answer ALL QUESTIONS

• ALL CODE MUST BE SAVED

Objective: 

• You will use 2 mini-programs in order to lock in use of variables and basic printing

• This should be saved in a python file: CH02.01A.py

  • • Both programs can be written in this file

    • This file should be uploaded to your DROPBOX

NEED TO KNOW THIS FIRST

To perform a basic print, you can do the following (TRY THESE):

count = 10

print("The Current Count is: ", count)

myvar = "Python"

print("I Like ", myvar, " because it is cool")

Activity 1: Meet The Heelers

Activity 2: Ice Cream Count

Activity 3: The Bluey Show Script 🎭

Bluey and Bingo are putting on a play. You’ll write a Python program that introduces the characters and acts out part of the script.

Instructions:

• Create variables for the characters’ names (bluey, bingo, bandit, chilli).

• Create variables for what each character will say in the play (bluey_line, bingo_line, bandit_line, chilli_line).

  • • Each line should be a string (like "Let’s play keepy-uppy!").

• Print a script where each line starts with the character’s name, followed by their line.