What is the regex for simply checking if a string contains a certain word (e.g. 'Test')? I've done some googling but can't get a straight example of such a regex. This is for a build script but has no bearing to any particular programming language.
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5 Answers
Just don't anchor your pattern:
/Test/
The above regex will check for the literal string "Test" being found somewhere within it.
4 Comments
GurdeepS
Thanks, I didn't know it was that simple! I definately didn't see this in my Googling. What do you mean by don't anchor my pattern?
David Clarke
You can anchor a pattern to match against the beginning or end of a string e.g. /^Test/ or /Test$/ respectively or even /^Test$/ to match exactly. The example is fatuous because it provides no benefit over comparing for equality but for example when doing form field validation a regex like /^\d+$/ will only match if the field contains at least one digit and nothing but numeric digits.
Xenolion
This Regex does not work for Kotlin probably Java as well. Use
^.*Test.*$
Benji
@Xenolion - Thank you! Couldn't get this to work in JavaScript to look for days of the week until I saw your comment:
dayRegx = /^.*((Monday)|(Tuesday)|(Wednesday)|(Thursday)|(Friday)|(Saturday)|(Sunday)).*$/gi; const containsDay = dayRegx.test(someStr);Assuming regular PCRE-style regex flavors:
If you want to check for it as a single, full word, it's \bTest\b, with appropriate flags for case insensitivity if desired and delimiters for your programming language. \b represents a "word boundary", that is, a point between characters where a word can be considered to start or end. For example, since spaces are used to separate words, there will be a word boundary on either side of a space.
If you want to check for it as part of the word, it's just Test, again with appropriate flags for case insensitivity. Note that usually, dedicated "substring" methods tend to be faster in this case, because it removes the overhead of parsing the regex.
2 Comments
strager
"
\b represents a "word boundary", that is, something which separates two words (e.g. a space)." \b does not match a space; it is an assertion which matches between characters (or at the beginning or end of a line, in most cases).
Michael Madsen
@strager: Yes, you're right - my explanation was a bit imprecise. I'll edit.
For Java use this: ^.*Test.*$.
It reads as: The string begins (^) then any character (.) can be repeated zero or more times (*) then Test and then again any character (.) repeated zero or more times (*) and the string ends ($).
3 Comments
FiddlingAway
This also works with regex search in SublimeText 3.
Yash Jain
Your wording for Test isn't clear. Let me fix it for anyone confused: It reads as: The string begins (^) then any character (.) can be repeated zero or more times () UP UNTIL Test is matched, and then again any character (.) repeated zero or more times () and the string ends ($).
ACV
@YashJain No I think your wording is more confusing. There is no UP UNTIL. This is not a loop. This just means you can have as many characters before Test and after as you want and you will still match this expression.
Depending on your flavor of regular expression - the exact details of regex capabilities vary depending on the language.
I will give javascript examples.
If you don't care about null safety...
str = "blah"
str.match(/a/)
// [ 'a', index: 2, input: 'blah', groups: undefined ]
Case-sensitive
/test/.test("does this string contain the word testtesttest")
// true
Case-insensitive
/test/i.test("Test")
Case-insensitive, ANY word
/\b\w+\b/i.test("bLAH")
// true
Comments
I'm a few years late, but why not this?
[Tt][Ee][Ss][Tt]
5 Comments
The Guy with The Hat
This answer turned up in the low quality review queue, presumably because you didn't explain the code. If you do explain it (in your answer), you are far more likely to get more upvotes—and the questioner actually learns something!
Platinum Azure
This isn't very generalizable-- imagine if the word you had to search for came from a user. You would have to generate the
[Aa] pattern for every letter and it would get pretty ugly pretty fast.
AmirJabari
Well, it was helpful for me. I was searching for any text that contains
. So I tried /[.]/. but /./ didn't work.
Kimball Robinson
If you want to find the word "Test" without being case-sensitive, you would do
/test/i.test(inputString) where the /i on the end makes it case-insensitive (javascript)
Danny van Holten
@AmirJabari, in regex a dot means: Matches any character except linebreaks. You would just need to escape the character:
/\./