Text is: "R1 AND R24 OR R456'
I want to write a pattern that can find R and the numbers (only numbers) following it. So the matches will be: R1, R24, R456.
How can I write appropriate regex?
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4 Answers
Something like
\bR\d+
See it here on Regexr
\b is a anchor for a word boundary, that means here there can be no word character (letter, number and _) before the R
\d is a digit
+ one or more
If you want to replace the numbers you can do so (if your language supports lookbehinds)
(?<=\bR)\d+
See here on Regexr
For the correct syntax you need to tell us your language.
Comments
The regex would be \bR\d+. To also capture the number you can use \bR(\d+).
Comments
/R\d+/
- /.../ represents a regex (you don't type them in all languages)
- R represents a literal character R
- \d represents a digit
\d+ represents "one or more" of whatever \d represents
As other people pointed out, you can use \b to represent a "beginning of word" if you want to avoid matching the end of words like "thumb2"
- You can replace by doing something like s/R(\d+)/rev_\1/g to turn R132 into rev_132 all through the text
The exact syntax of how to apply a regex varies from language to language: in Perl, you type something very like the /.../ syntax above. In other languages, you may use a string "R\d+" passed to a function. In some you need the slashes inside a string.
You can test it online, eg: http://www.fileformat.info/tool/regex.htm
- There are many online introductions, eg: http://www.regular-expressions.info/reference.html
1 Comment
Jack V.
Yeah. The first pass had <!--xxxxxxxxxxxxxxxxxxxxx--> so I could give a 6 character answer, but I decided that if I was going to answer it at all, I should at least explain.
The topic of your question says "Replace" but I can't find any points concerning possible replacement in your question.
The regex pattern /R[0-9]+/ should work to find "R1", "R24", and "R456" in "R1 AND R24 OR R456".
To extract the numbers following the respective "R" you can add a group to the regex pattern: /R([0-9]+)/. Then you can just "match" the test string against the regex pattern and extract group 1 for each match:
Target String: R1 AND R24 OR R456
Regex Pattern: R([0-9]+)
"find next"; group(0): R1; group(1): 1
"find next"; group(0): R24; group(1): 24
"find next"; group(0): R456; group(1): 456
"find next"; null
Which programming language are you using? We could then provide an even concreter example.
2 Comments
Ahmet Altun
I forgot to ask about replace. I need to get number part of the match. I suppose we can make groups in regex. How can I?
Flinsch
I edited my post to also address the extraction of the numbers. Maybe you tell us your programming language you are using the regex within. Then we could give a concrete example.