97 – Match word boundaries

The special character \b can be used to match word boundaries in regular expressions. The special character \B, on the other hand, only matches inside words.

By combining \b and \B you can match prefixes, suffixes, standalone words, and more.

As an example, consider the sentence “watermelon is 92% water!” and three different patterns:

1. The pattern r"water" matches the five characteres “water” in sequence, so it would match the two occurrences of “water” in the sentence given.

2. The pattern r"\bwater\b" matches “water” as a standalone word, so it would only match the word at the end of the string.

3. The pattern r"\bwater\B" matches “water” as a prefix, so it would only match the string “water” that is a substring of the word “watermelon” at the beginning of the sentence.