Variables

Variables are used to store data that can be used and manipulated throughout your program. In Python, you don't need to declare the type of a variable; it is dynamically typed.

Assignments

Assignment is the process of storing a value in a variable. The assignment operator in Python is the equals sign (=).

Identifiers

Identifiers are names given to variables, functions, classes, etc. They must follow certain rules:

• Must begin with a letter (a-z, A-Z) or an underscore (_)
• Can contain letters, digits (0-9), and underscores
• Case-sensitive (e.g., myVar and myvar are different)
• Cannot be a reserved keyword in Python (e.g., if, else, for, etc.)

Examples

Variable Assignment

Using Identifiers

  # Valid identifiers
age = 25
first_name = "John"
_number = 42 

# Invalid identifiers (uncommenting these lines will cause an error)
# 1st_variable = 10  # Cannot start with a digit
# my-variable = 20   # Hyphens are not allowed
# class = "Math"     # 'class' is a reserved keyword

Reassigning Variables

You can reassign variables to new values, and even change their types:

Best Practices

• Use meaningful variable names to make your code readable and maintainable.
• Follow the PEP 8 style guide for Python code, which recommends using lowercase letters and underscores for variable names (snake_case).

By understanding and using variables, assignments, and identifiers correctly, you can write clear and efficient Python code.