To match whole exact words, use the word boundary metacharacter '\b'. What if you want to match only whole words-not exact substrings? Here’s an example: > 'no' in 'nobody knows'Īnd another example: > re.search('see', 'dfjkyldsssseels')
#REGEX WORD BOUNDARY HOW TO#
Is this what you wanted? If not, read on: How to Match a Word in a String (Word Boundary \b)?Īn exact match of a word will also retrieve matching substrings that occur anywhere in the string. When searching for the exact word 'good' in the string 'goodbye' it actually matches the prefix of the word. Using the previous approach does not help because you’re getting prefix matches of your searched word: > re.search('good', 'goodbye') This returns a match object that wraps a lot of useful information such as the start and stop matching positions and the matching substring.Īs you’re looking for exact string matches, the matching substring will always be the same as your searched word.īut wait, there’s another problem: you wanted an exact match, right? ? Related Tutorial: If you’re unsure about the re.search() method, check out my detailed tutorial on this blog. Here’s how you can match an exact substring in a given string: > import reĪfter importing Python’s library for regular expression processing re, you use the re.search(pattern, string) method to find the first occurrence of the pattern in the string.
For example, you can call re.search('hello', 'hello world') to match the exact string 'hello' in the string 'hello world' and return a match object. To match an exact string using Python’s regex library re, use the string as a regex. So let’s explore the problem of exact string matching using the regex library next: How to Match an Exact String (Regex)? However, the advantage of Python’s regular expression library re is that it returns a match object which contains more interesting information such as the exact location of the matching substring. The negative membership operator s1 not in s2 returns True if string s1 does not occur in string s2.īut there’s a problem with the membership operator. You can also check whether a string does not occur in another string. This is called the membership operator and it’s very efficient. The first example shows the most straightforward way of doing it: simply ask Python whether a string is “in” another string. Thus, you should rely on this method if possible: > 'hello' in 'hello world' As this is a very efficient built-in functionality in Python, it’s much faster, more readable, and doesn’t require external dependencies.
Instead of matching an exact string, it’s often enough to use Python’s in keyword to check membership. This is the simple answer, you’ve already learned. To match an exact string 'hello' in a string such as 'hello world', use the in keyword within membership expression 'hello' in 'hello world'. How to Check Membership of a Word in a String (Python Built-In)? How to Find All Lines Not Containing an Exact Word?.How to Find All Lines Containing an Exact Word?.How to Find All Occurrences of a Word in a String?.How to Match a Word in a String (Case Insensitive)?.How to Match a Word in a String (Word Boundary \b)?.How to Check Membership of a Word in a String (Python Built-In)?.Let’s dive into each of them in the remaining article to learn and improve your regex superpowers! How to find all lines containing an exact word?.How to find all occurrences of a word in a string?.How to match a word in a string (case insensitive)?.How to match a word in a string using word boundaries \b?.How to match an exact string using Python’s regex library?.How to check membership of a word in a string using no library?.In fact, there are multiple ways of understanding your question and I have tried to find all interpretations and answered them one by one in this tutorial: But let’s dive into some more specific questions-because you may not exactly have looked for this simplistic answer.
#REGEX WORD BOUNDARY CODE#
Feel free to play the tutorial video as you go over the article.ĭo you want to master the regex superpower? Check out my new book The Smartest Way to Learn Regular Expressions in Python with the innovative 3-step approach for active learning: (1) study a book chapter, (2) solve a code puzzle, and (3) watch an educational chapter video.