What are the Types and How to Resolve Unexpected Indent Errors in Python?

Unexpected Indent: A Common Python Dilemma

In Python, the arrangement of code blocks is crucial, and "unexpected indent" errors can arise when the indentation of code lines conflicts with the expected structure. Let's explore the types of unexpected indent errors and how to resolve them.

Unexpected Indent

This error occurs when a line has more indentation than its preceding line but does not belong to a valid subblock. Code blocks, such as those following if, while, or for statements, must have consistent indentation throughout.

For example:

<code class="python">def a():
  print "foo"
    print "bar"  # Error: unexpected indent</code>

In this case, the second line is indented more than the first, violating the consistent indentation rule.

Unindent Does Not Match

This error occurs when a line has fewer indentation spaces than its preceding line, but it does not align with any outer indentation level. Python is unable to determine the correct indentation level for the line.

For example:

<code class="python">if user == "Joey":
  print "Super secret powers enabled!"
print "Revealing super secrets"  # Error: unindent does not match</code>

The last line should have the same indentation as the line preceding it, or less indentation if the code block started by if user == "Joey" has ended.

Expected an Indented Block

This error occurs when a line is not indented properly to match its preceding line, which is expected to start a block, such as an if, while, or for statement, or a function definition.

For example:

<code class="python">def foo():
  print "Bar"  # Error: expected an indented block</code>

To avoid this error, use pass if you need a no-operation function:

<code class="python">def foo():
  pass</code>

Tips for Avoiding Indentation Errors

To eliminate "unexpected indent" errors, follow these guidelines:

• Use consistent indentation (e.g., 4 spaces or 2 tabs) throughout your code.
• Avoid mixing tabs and spaces.
• Use a good IDE that handles indentation automatically.
• Proofread your code carefully for any indentation discrepancies.

By adhering to these guidelines, you can prevent indentation errors and improve the readability and maintainability of your Python code.

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