Kursinnehåll

Introduction to Python (copy)

1. Getting Started

First Steps Comments Simple Math: Add & Subtract Simple Math: Multiply & Divide Recap

2. Variables and Types

Data Types Storing Data in Variables Variable Naming Rules Using Variables String Indexing and Length String Slicing and Concatenation Challenge: Inventory Sorting Capstone Recap

3. Conditional Statements

Boolean Data Type Combining Conditions Challenge: Boolean Logic Membership Operators and Type Comparisons Conditional Expressions Challenge: Product Management Capstone Recap

4. Other Data Types

Lists and List Methods Nested Lists Challenge: List Management Tuples and Tuple Methods Tuple Operations Challenge: Tuple Operations Dictionaries and Dictionary Methods Challenge: Pricing Adjustment Capstone Recap

5. Loops

For Loops While Loops Range Function Iterating Over Indexes Challenge: Sales and Shipments Nested Loops Challenge: Automating Stock Control Challenge: Solo Coding Capstone Recap

6. Functions

Built-in Functions Challenge: Zip and Sort Functions User Defined Functions List Behavior in Functions Functions with no Return Modifying Functions Challenge: Product Revenues Capstone Recap

Variable Naming Rules

Fantastic progress! Now, let's dive into something foundational yet crucial — naming your variables. Like every item in your grocery store has a specific place and label, each variable in Python must be named thoughtfully. Good naming helps you and others understand what your code does at a glance.

Watch as Alex explains the variable naming rules and how these work in practice:

Rules for Naming Variables

Always Start with a Letter or an Underscore

Variable names must start with a letter or an underscore, like item_name or _price. Don't start a variable name with a number (e.g., 2item is invalid).

Use Only Letters, Numbers, and Underscores

Variable names should only contain letters, numbers, and underscores. For example, item_name1 is fine, but avoid using special characters like dashes (item-name is invalid).

Be Aware of Case Sensitivity

Python treats uppercase and lowercase letters as different. So, item and Item are two separate variables in Python.

Don't Use Python's Reserved Words

Avoid using Python's built-in keywords (like print, if, and type) as variable names, as these are already used for special purposes in the language.

Example of Proper Variable Naming

In the following example, all variable naming rules are followed, ensuring that the variables are named correctly and the code will run smoothly:


              123456
            
# Correct variable names
item_name = "Apple"
_item_price = 0.99
item1_quantity = 10
storeName = "Green Valley Groceries"
print(item_name, _item_price, item1_quantity, storeName)

Example of Incorrect Naming

In the following example, variable naming rules are not followed, resulting in errors and issues when running the code:


              123456
            
# Incorrect variable names 
1item = "Banana" # Variables cannot start with a number. Instead try `item_one`, or `oneItem`
item-name = "Orange" # Variables cannot contain a dash (-), use underscores (_) instead. For example `item_name` is a valid variable 
print = 5.0 # You cannot use reserved keywords as a variable
# But you can use these words in combination with others to name a variable
# For example, `print_quantity = 5.0` is valid.

Note

You can attempt to correct the variable names above to ensure the code runs without errors.

Properly named variables enhance code readability and maintainability. Following Python's naming conventions is crucial to avoid syntax errors and other potential issues.

Uppgift

Swipe to start coding

Create and print variables that describe a grocery item — "Bread". Define variables for its name, price per loaf, and stock quantity, using clear and descriptive names.

Code Instructions

Create a variable item_name and assign it the string "Bread".
Create a variable item_price and assign it the float 4.52 (price per loaf).
Create a variable items_in_stock and assign it the integer 230 (quantity available).
Use these variables in print() statements to display the item’s details.

Output Requirements

Print the item information in the following format:

Item: <item_name>
Price per loaf: $ <item_price>
Quantity in stock: <items_in_stock>

Lösning

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 2. Kapitel 3

Variable Naming Rules

Watch as Alex explains the variable naming rules and how these work in practice:

Rules for Naming Variables

Always Start with a Letter or an Underscore

Variable names must start with a letter or an underscore, like item_name or _price. Don't start a variable name with a number (e.g., 2item is invalid).

Use Only Letters, Numbers, and Underscores

Variable names should only contain letters, numbers, and underscores. For example, item_name1 is fine, but avoid using special characters like dashes (item-name is invalid).

Be Aware of Case Sensitivity

Python treats uppercase and lowercase letters as different. So, item and Item are two separate variables in Python.

Don't Use Python's Reserved Words

Avoid using Python's built-in keywords (like print, if, and type) as variable names, as these are already used for special purposes in the language.

Example of Proper Variable Naming

In the following example, all variable naming rules are followed, ensuring that the variables are named correctly and the code will run smoothly:


              123456
            
# Correct variable names
item_name = "Apple"
_item_price = 0.99
item1_quantity = 10
storeName = "Green Valley Groceries"
print(item_name, _item_price, item1_quantity, storeName)

Example of Incorrect Naming

In the following example, variable naming rules are not followed, resulting in errors and issues when running the code:


              123456
            
# Incorrect variable names 
1item = "Banana" # Variables cannot start with a number. Instead try `item_one`, or `oneItem`
item-name = "Orange" # Variables cannot contain a dash (-), use underscores (_) instead. For example `item_name` is a valid variable 
print = 5.0 # You cannot use reserved keywords as a variable
# But you can use these words in combination with others to name a variable
# For example, `print_quantity = 5.0` is valid.

Note

You can attempt to correct the variable names above to ensure the code runs without errors.

Properly named variables enhance code readability and maintainability. Following Python's naming conventions is crucial to avoid syntax errors and other potential issues.

Uppgift

Swipe to start coding

Create and print variables that describe a grocery item — "Bread". Define variables for its name, price per loaf, and stock quantity, using clear and descriptive names.

Code Instructions

Create a variable item_name and assign it the string "Bread".
Create a variable item_price and assign it the float 4.52 (price per loaf).
Create a variable items_in_stock and assign it the integer 230 (quantity available).
Use these variables in print() statements to display the item’s details.

Output Requirements

Print the item information in the following format:

Item: <item_name>
Price per loaf: $ <item_price>
Quantity in stock: <items_in_stock>

Lösning

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 2. Kapitel 3

Byt till skrivbordet för praktisk övningFortsätt där du är med ett av alternativen nedan