Re^2: Regex pattern that fails when string contains a certain pattern

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Re^3: Regex pattern that fails when string contains a certain pattern by Corion (Patriarch) on Dec 22, 2016 at 09:42 UTC
Since I'm not going to test my regular expressions and since you don't seem to want to provide a SSCCE, let us think about a different approach, rephrasing your problem: If your string contains an underscore, you want that underscore to be followed by letters and then a number. If your string contains no underscore, you want to accept it. When you lok at these two statements, it should be simple for you to encode that as two separate `if` statements. If you really want to force this into one regular expression, consider a simple alternation: `/^([^_]+\|[^_]+_[a-z]+\d[^_]*)$/` [download] ("Either the string contains no underscore, or it contains stuff that is no underscore, followed by an underscore, letters and a digit, and then no underscores again"). Of course, this is all vague since you don't provide code to discuss.	[reply] [d/l] [select]
Re^4: Regex pattern that fails when string contains a certain pattern by hoppfrosch (Scribe) on Dec 22, 2016 at 09:49 UTC
I'm willing to provide code - but I have to write it first. I tested my pattern within a regex-testing GUI.	[reply]
Re^5: Regex pattern that fails when string contains a certain pattern by Corion (Patriarch) on Dec 22, 2016 at 09:51 UTC
After you've added some more specifications, let me recommend that you don't use a single regular expression. While it is still possible to create a regular expression that matchess your description, three `if` statements convey your rules much better.	[reply] [d/l]
Re^3: Regex pattern that fails when string contains a certain pattern by kcott (Archbishop) on Dec 22, 2016 at 18:01 UTC
Corion wrote: "`/_[a-z]+\d/`" You responded: "Your pattern does not match the second example: aa1_bb2" `$ perl -E '"aa1_bb2" =~ /_[a-z]+\d/ && say "Yes, it does!"' Yes, it does!` [download] — Ken	[reply] [d/l] [select]