1.3 Deep Dive into Python Variables and Naming

 In Python, a variable is essentially a name given to a memory location where you can store data. This data can be of different types, such as numbers, text, or even more complex structures. Unlike many other programming languages, Python doesn't require you to declare the variable's type beforehand. Its type is determined dynamically based on the value assigned to it.

Identifier Naming

An identifier is simply the name of a variable. Python has specific rules for naming variables:

• Must start with a letter (uppercase or lowercase) or an underscore (_).
• Can contain letters, numbers, or underscores.
• Case-sensitive (age, Age, and AGE are different variables).
• Cannot be a reserved keyword (like if, else, for, etc.).

Good naming practices:

• Use descriptive names that reflect the variable's purpose (e.g., customer_name, product_price).
• Use lowercase with underscores for multiple words (e.g., total_amount).
• Avoid single-letter names unless the meaning is clear from the context.

Declaring Variables and Assigning Values

In Python, you declare a variable simply by assigning a value to it. There's no explicit declaration syntax.

Python

x = 10  # Assigning an integer value to x
name = "Alice"  # Assigning a string value to name
is_active = True  # Assigning a boolean value to is_active

Object References

When you assign a value to a variable, Python creates an object in memory to hold that value. The variable then becomes a reference to that object.

Python

a = 10
b = a

In this example, both a and b refer to the same integer object with the value 10. Changing the value of one variable will not affect the other unless you reassign it.

The type() Function

To determine the data type of a variable, you can use the type() function:

Python

x = 10
print(type(x))  # Output: <class 'int'>

name = "Alice"
print(type(name))  # Output: <class 'str'>

Key Points to Remember

• Python is dynamically typed, meaning variable types are determined at runtime.
• Variable names should be descriptive and meaningful.
• Use consistent naming conventions for better readability.
• Understand the concept of object references to avoid unexpected behavior.
• Utilize the type() function to inspect variable types.

By following these guidelines, you'll write cleaner, more efficient, and maintainable Python code.