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Python Regular Expressions in Python Introduction to Regular Expressions Sets

Mona Jalal
Mona Jalal
4,302 Points

confusion about \b

so when to use each?

print(re.findall(r'\b[trehous]{9}\b', names, re.I))
print(re.findall(r'[trehous]{9}', names, re.I))

1 Answer

Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

The regex character \b represents a zero-length position at a word boundary. It is used if you are looking for whole words and reject matches that may be inside other words.

In your example, ypu would you'd the \b to say "I am looking for a sequence of 9 characters from this set but not sequences that are within sequences of 10 or more characters.

This means using \b would reject matching "treehouses" since 9 characters aren't surrounded by word boundaries.