Boundaries

Lesson 13 of 28 in Coddy's RegEx in Python course.

Word boundaries are used to match positions where a word starts or ends. The two main word boundary markers are \b and \B.

<strong>\b</strong>: Matches a word boundary, the position where a word starts or ends.
<strong>\B</strong>: Matches a non-word boundary, the position where there isn't a word boundary.

import re

text = "cat scatter cater"
pattern = r"\bcat\b"

matches = re.findall(pattern, text)

print(matches)  # Output: ['cat']

In the above example, the pattern \bcat\b matches the word "cat" only when it appears as a whole word, thanks to the word boundary markers \b on either side.

Challenge

Easy

Write a function named find_whole_words that takes a text string and a word as input, and returns a list of all occurrences of the whole word in the text.

Try it yourself

import re

def find_whole_words(text, word):
    # Write code here

All lessons in RegEx in Python

1Introduction

Introduction

4Anchors and Quantifiers

AnchorsBoundariesQuantifiers Repetitions

7Final Challenges

Extracting Hashtags Finding Email Addresses Valid Phone Numbers Finding Dates Capitalized Words

2re Library

findall search split sub

5Grouping and Advanced Patterns

Grouping Capturing Pipe Operator Alternation Lookaheads Lookbehinds

3Basic Pattern Syntax

Basic Metacharacters Literals Character Classes Ranges Common Predefined Classes Advanced Predefined Classes

6Advanced Techniques

Escape Metacharacters Escape Sequences