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I want to create a regexp in Emacs that matches exactly 3 digits. For example, I want to match the following:
123 345 789 But not
1234 12 12 23 If I use [0-9]+ I match any single string of digits. I thought [0-9]{3} would work, but when tested in re-builder it doesn't match anything.
656
\d (digit) matches any single digit (same as [0-9] ). The uppercase counterpart \D (non-digit) matches any single character that is not a digit (same as [^0-9] ). \s (space) matches any single whitespace (same as [ \t\n\r\f] , blank, tab, newline, carriage-return and form-feed).
The ‹ ^ › and ‹ $ › anchors ensure that the regex matches the entire subject string; otherwise, it could match 10 characters within longer text. The ‹ [A-Z] › character class matches any single uppercase character from A to Z, and the interval quantifier ‹ {1,10} › repeats the character class from 1 to 10 times.
match(/(\d{5})/g);
Real number regex can be used to validate or exact real numbers from a string.
If you're entering the regex interactively, and want to use {3}, you need to use backslashes to escape the curly braces. If you don't want to match any part of the longer strings of numbers, use \b to match word boundaries around the numbers. This leaves:
\b[0-9]\{3\}\b For those wanting more information about \b, see the docs:
matches the empty string, but only at the beginning or end of a word. Thus,
\bfoo\bmatches any occurrence offooas a separate word.\bballs?\bmatchesballorballsas a separate word.\bmatches at the beginning or end of the buffer regardless of what text appears next to it.
If you do want to use this regex from elisp code, as always, you must escape the backslashes one more time. For example:
(highlight-regexp "\\b[0-9]\\{3\\}\\b") 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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