techmore.in

Python - Indentation

What is Indentation?

In Python, indentation refers to the whitespace at the beginning of a line. Unlike many programming languages that use curly braces {} to define code blocks, Python uses indentation to represent blocks of code.

Why is Indentation Important?

  • It defines the **structure** and **scope** of code.
  • Python throws an IndentationError if indentation is not correct.
  • Makes code more readable and clean.

How to Use Indentation?

Use 4 spaces (recommended by PEP 8) or a tab. Be consistent across your file.

python
def greet(): print("Hello, World!") # This line is indented by 4 spaces greet()

When Does Indentation Matter?

  • In function definitions
  • In loops (for, while)
  • In conditionals (if, else, elif)
  • In classes
  • Any place where a block of code is expected

Correct vs Incorrect Indentation

Correct
for i in range(3): print("Count:", i)

Incorrect
for i in range(3): print("Count:", i)# IndentationError!

Pros and Cons

Pros

  • Enforces clean and readable code
  • No need for curly braces
  • Structure is visually clear

Cons

  • Whitespace errors are harder to spot
  • Mixing tabs and spaces causes bugs
  • Not beginner-friendly at first

Best Practices

  • Use 4 spaces per indentation level (PEP 8)
  • Don’t mix tabs and spaces
  • Use linters (e.g., Flake8) or IDE support