Variables in Python

Understanding Variables

In Python, a variable is a named storage location that holds a value. It's like a container that can store different types of data. Think of it as a label you attach to a piece of information.

Key characteristics of variables:

• Name: A unique identifier chosen by the programmer.

• Value: The data stored in the variable.

• Data type: The type of data the variable holds (e.g., integer, float, string, boolean).

Declaring Variables

In Python, you don't explicitly declare the data type of a variable. The interpreter automatically determines the data type based on the assigned value.

Python

x = 10  # Integer

name = "Alice"  # String

is_student = True  # Boolean

Variable Naming Conventions

• Use descriptive names that reflect the variable's purpose.

• Start with a letter (uppercase or lowercase) or an underscore (_).

• Can contain letters, numbers, and underscores.

• Avoid using Python keywords as variable names.

Assigning Values

You assign a value to a variable using the equal sign (=).

Python

age = 30

price = 9.99

Dynamic Typing

Python is dynamically typed, meaning the data type of a variable can change during program execution.

Python

x = 10  # x is an integer

x = "hello"  # x is now a string

Best Practices

• Use meaningful variable names.

• Avoid single-letter variable names unless they are well-understood context (e.g., loop counters).

• Use consistent naming conventions (e.g., camelCase, snake_case).

• Consider using constants for values that don't change.

Example

Python

# Good variable names

student_name = "John Doe"

total_score = 95

# Bad variable names

x = 10  # Unclear meaning

a1b2 = "value"  # Confusing

Additional Notes

• Variables are case-sensitive, so age and Age are different variables.

• You can use multiple assignment to assign values to multiple variables simultaneously:

Python

x, y, z = 1, 2, 3

By understanding these concepts, you can effectively use variables to store and manipulate data in your Python programs.