Understanding and Fixing the IndentationError: expected an indented block after 'if' statement in Python

Python is renowned for its clean and readable syntax, which includes its use of indentation to define blocks of code. One common issue beginners (and sometimes even experienced developers) encounter is the IndentationError: expected an indented block after 'if' statement. This error can be frustrating, but understanding its cause and how to fix it can save a lot of time and hassle.
In this blog, we’ll explore what triggers this error and how to resolve it effectively.

What is the IndentationError: expected an indented block after 'if' statement?
The IndentationError in Python occurs when the interpreter expects an indented block of code but doesn’t find one. Specifically, when you use control structures like if, for, while, or try, Python expects an indented block following these statements to define the scope of the code that should be executed. If this indentation is missing, Python raises an IndentationError.

Example of the Error
x = 10
if x > 5:
print("x is greater than 5")

When you run this code, Python will throw an IndentationError like this:
ERROR!
Traceback (most recent call last):
  File "<main.py>", line 3
    print("x is greater than 5")
    ^^^^^
IndentationError: expected an indented block after 'if' statement on line 2

=== Code Exited With Errors ===

Why Does This Error Occur?
In Python, indentation is used to define blocks of code. For example, after an if statement, you need to indent the code that should execute if the condition is true. This indentation can be spaces or tabs, but it must be consistent. The error occurs because Python expects an indented block to follow the if statement, and if it doesn’t find it, it raises an error.

How to Fix the Error
To resolve this error, you need to provide an indented block of code following the if statement. Here’s how you can correct the example:

x = 10
if x > 5:
    print("x is greater than 5")

In this corrected version, the print statement is indented with four spaces (or a tab, depending on your editor's configuration). This indentation indicates that print("x is greater than 5") is part of the if block and should be executed when x > 5 evaluates to True.

Best Practices for Indentation in Python
    Consistent Indentation: Use either spaces or tabs for indentation, but do not mix them. The Python community typically prefers 4 spaces per indentation level.
    Editor Configuration: Most modern code editors and IDEs can be configured to automatically insert spaces when you press the tab key, which helps avoid mixing tabs and spaces.
    Check Indentation: If you encounter indentation errors, double-check that all blocks of code are properly indented and that your editor is set up correctly.
    Use Linters: Tools like flake8 or pylint can help catch indentation issues and other coding standards violations before you run your code.