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I am trying to search for all occurrences of "Tom" which are not followed by "Thumb".
I have tried to look for
Tom ^((?!Thumb).)*$ but I still get the lines that match to Tom Thumb.
911
If you want to exclude a certain word/string in a search pattern, a good way to do this is regular expression assertion function. It is indispensable if you want to match something not followed by something else. ?= is positive lookahead and ?! is negative lookahead.
The metacharacter \b is an anchor like the caret and the dollar sign. It matches at a position that is called a “word boundary”. This match is zero-length. There are three different positions that qualify as word boundaries: Before the first character in the string, if the first character is a word character.
Example: "a\+" matches "a+" and not a series of one or "a"s. ^ the caret is the anchor for the start of the string, or the negation symbol. Example: "^a" matches "a" at the start of the string. Example: "[^0-9]" matches any non digit. $ the dollar sign is the anchor for the end of the string.
If you add a * after it – /^[^abc]*/ – the regular expression will continue to add each subsequent character to the result, until it meets either an a , or b , or c . For example, with the source string "qwerty qwerty whatever abc hello" , the expression will match up to "qwerty qwerty wh" .
In case you are not looking for whole words, you can use the following regex:
Tom(?!.*Thumb) If there are more words to check after a wanted match, you may use
Tom(?!.*(?:Thumb|Finger|more words here)) Tom(?!.*Thumb)(?!.*Finger)(?!.*more words here) To make . match line breaks please refer to How do I match any character across multiple lines in a regular expression?
See this regex demo
If you are looking for whole words (i.e. a whole word Tom should only be matched if there is no whole word Thumb further to the right of it), use
\bTom\b(?!.*\bThumb\b) See another regex demo
Note that:
\b - matches a leading/trailing word boundary(?!.*Thumb) - is a negative lookahead that fails the match if there are any 0+ characters (depending on the engine including/excluding linebreak symbols) followed with Thumb.
39
You don't say what flavor of regex you're using, but this should work in general:
Tom(?!\s+Thumb) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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