Variable Naming Rules
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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.
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.
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