1

I started learning regex recently. I know that * modifier means match 0 or more times while + modifier means match 1 or more times.

However when you use these modifiers with square brackets, how will the code get parsed? It seems to me that using square brackets would equalize the + and *.

For example: What is the difference between [\w\s,:]+ and [\w\s,:]*?

Improve this question

1 Answer 1

Reset to default
2

The difference is exactly that you wrote. The characters in the set may occur once to multiple times with + and may also not occur at all with * .

Improve this answer
5
  • so [...|]+ will be equal to [...]*?
    – One Face
    Commented Feb 11, 2015 at 0:35
  • 1
    Ummm ... no. [] defines a character class. Adding a pipe symbol to that won't do what you think it does. It's NOT grouping. Also three dots inside [] don't make sense. They're literals in there.
    – tink
    Commented Feb 11, 2015 at 0:38
  • 1
    @C Rags: Assuming your dots stand for any set of characters. No, they are not the same. The left one will match any non-empty sequence of those characters plus the pipe character, while the right one will only match sequences of those characters in any amount including zero.
    – Janis
    Commented Feb 11, 2015 at 0:52
  • 4
    @CRags, no, but ([...]+|) will be equal to [...]*
    – Mark
    Commented Feb 11, 2015 at 1:10
  • Also, [abc][abc]*, [abc]*[abc], and [abc]+ are all equivalent.
    – Scott - Слава Україні
    Commented Feb 11, 2015 at 4:20

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .