indentation-error.md

Error: IndentationError

The Error

IndentationError: unexpected indent
IndentationError: expected an indented block
TabError: inconsistent use of tabs and spaces in indentation

Common Causes

1. Mixed tabs and spaces — most common cause of TabError
2. Wrong indentation level — indented too much or too little
3. Missing block body — empty if/for/while block without pass
4. Copy-paste with different indentation

Quick Fix

# Convert all tabs to spaces (4 spaces per tab)
expandtabs file.py > fixed.py

# Check for mixed tabs/spaces
python -m py_compile file.py

# Or use autopep8 to auto-fix
pip install autopep8
autopep8 --in-place file.py

Detailed Solution

Solution 1: Use Spaces (Not Tabs) Consistently

# ❌ Mixed tabs and spaces (TabError)
def greet(name):
	print("Hello")      # ← tab
    print(name)         # ← spaces

#  All spaces (4 per level is PEP 8 standard)
def greet(name):
    print("Hello")
    print(name)

Solution 2: Empty Blocks Need pass

# ❌ Syntax error — block can't be empty
def future_feature():

for item in items:

#  Use pass as placeholder
def future_feature():
    pass

for item in items:
    pass

Solution 3: Configure Your Editor

VSCode settings (settings.json):
"editor.tabSize": 4,
"editor.insertSpaces": true,
"editor.detectIndentation": false,
"[python]": {
    "editor.tabSize": 4,
    "editor.insertSpaces": true
}

Prevention

• Configure your editor to use spaces for Python
• Use a linter: flake8 or pylint
• Format with black: pip install black && black file.py

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