The notion that regex doesn’t support inverse matching is not entirely true. You can mimic this behavior by using negative look-arounds: ^((?!hede).)*$ Non-capturing variant: ^(?:(?!:hede).)*$ The regex above will match any string, or line without a line break, not containing the (sub)string ‘hede’. As mentioned, this is not something regex is “good” at (or should … Read more
.* If the users want to give you their phone numbers, then trust them to get it right. If they do not want to give it to you then forcing them to enter a valid number will either send them to a competitor’s site or make them enter a random string that fits your regex. … Read more
Make .* non-greedy by adding ‘?‘ after it: Project name:\s+(.*?)\s+J[0-9]{7}:
The most important part is the concepts. Once you understand how the building blocks work, differences in syntax amount to little more than mild dialects. A layer on top of your regular expression engine’s syntax is the syntax of the programming language you’re using. Languages such as Perl remove most of this complication, but you’ll … Read more
The fully RFC 822 compliant regex is inefficient and obscure because of its length. Fortunately, RFC 822 was superseded twice and the current specification for email addresses is RFC 5322. RFC 5322 leads to a regex that can be understood if studied for a few minutes and is efficient enough for actual use. One RFC … Read more
Using Perl: # Match all lines that start with a-z or A-Z and are followed by a space perl -ne ‘print if m/^[a-z]+\s/i’ file Using awk: # Match first field’s that only contain a-z or A-Z awk ‘$1 ~ /^[a-zA-Z]+$/’ file Both will output: CABMEL 1873 1 1 CABMEL 1874 1 1 CABMEL 1875 1 … Read more
You’ve already got a working answer but just in case you are curious what was wrong with your original approach, the answer is that you need parentheses around your alternation otherwise the (\.|$) is only required if the number is less than 200. ‘\b((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)(\.|$)){4}\b’ ^ ^
The Stack Overflow Regular Expressions FAQ See also a lot of general hints and useful links at the regex tag details page. Online tutorials RegexOne ↪ Regular Expressions Info ↪ Quantifiers Zero-or-more: *:greedy, *?:reluctant, *+:possessive One-or-more: +:greedy, +?:reluctant, ++:possessive ?:optional (zero-or-one) Min/max ranges (all inclusive): {n,m}:between n & m, {n,}:n-or-more, {n}:exactly n Differences between greedy, … Read more