CODEWITHSUNDEEP
javascriptregex
danbruegge
danbruegge

Reputation: 2243

Need help to find the right regex pattern to match

my RegEx is not working the way i think, it should.

[^a-zA-Z](\d+-)?OSM\d*(?![a-zA-Z])

I will use this regex in a javascript, to check if a string match with it.

Should match:
12345612-OSM34
12-OSM34
OSM56
7-OSM
OSM

Should not match:
-OSM
a-OSM
rOSMann
rOSMa
asdrOSMa
rOSM89
01-OSMann
OSMond
23OSM
45OSM678

One line, represents a string in my javascript.

https://www.regex101.com/r/xQ0zG1/3

The rules for matching:

I Hope someone can help.

Upvotes: 1

Views: 105

Answers (2)

Domino
Domino

Reputation: 6768

[^a-zA-Z](\d+-)?OSM\d*(?![a-zA-Z])

  • [^a-zA-Z] In regex, you specify what you want, not what you don't want. This piece of code says there must be one character that isn't a letter. I believe what you wanted to say is to match the start of a line. You don't need to specify that there's no letter, you're about to specify what there will be on the line anyway. The start of a regex is represented with ^ (outside of brackets). You'll have to use the m flag to make the regex multi-line.

  • (\d+-)? means one or more digits followed by a - character. The ? means this whole block isn't required. If you don't want foreign digits, you might want to use [0-9] instead, but it's not as important. This part of the code, you got right. However, if you don't need capture blocks, you could write (?:) instead of ().

  • \d*(?![a-zA-Z]) uses lookahead, but you almost never need to do that. Again, specifying what you don't want is a bad idea because then I could write OSMé and it would match because you didn't specify that é is forbidden. It's much simpler to specify what is allowed. In your case since you want to match line ends. So instead, you can write \d*$ which means zero or more digits followed by the end of the line.

/^(?:\d+-)?OSM\d*$/gm is the final result.

Upvotes: 1

hjpotter92
hjpotter92

Reputation: 80639

You can use the following simplified pattern using anchors:

^(?:\d+-)?OSM\d*$

The flags needed (if matching multi-line paragraph) would be: g for global match and m for multi-line match, so that ^ and $ match the begin/end of each line.

EDIT

Changed the (\d+-) match to (?:\d+-) so that it doesn't group.

Upvotes: 4

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