regular expression what does \d+? mean?

Asked Apr 30 '15 at 09:06

Active Apr 30 '15 at 09:10

Viewed 51 times

I'm new to regular expression using javascript.

I know \d+ means one or more number(s), but the following ? really confused me! I tried some possibilities: 1.it means zero or more numbers, but /\d+?/.test("a") returns false 2.it means one number followed by zero or one +, but "11+".split(/\d+?/) returns ["","","+"] (all these codes are in JavaScript) So it seems like it means exactly one number!?

Thanks for all responses and advice!

edited Apr 30 '15 at 09:10

Andy

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asked Apr 30 '15 at 09:06

Pufan Jiang

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Java != Javascript. This question doesn't involve Java at all. – JonK Apr 30 '15 at 09:07
You can try this for test your pattern : https://www.debuggex.com/ . I think that don't change anything. – Gilles Apr 30 '15 at 09:09
@Pufan check http://stackoverflow.com/questions/15805907/meaning-of-a-regular-expression-d-d – Arasu Apr 30 '15 at 09:11
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@Andy absolutely *not*. It means an *ungreedy* one or more numbers. – Lucas Trzesniewski Apr 30 '15 at 09:18
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Basically, it will always match one number in this case since it's *lazy* (ungreedy). I would just write `/\d/` to clear all confusions. – HamZa Apr 30 '15 at 09:22

regular expression what does \d+? mean?

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