using regex to capture / inclusive and select characters after

Question

I have the regular expression

[/].([a-z/!@$%^&*()-+><~*\.]+)

which I am trying to capture everything after the / (inclusive) up to a # or ? (exclusive).

The strings I have tried the regex on:

/hello.there#test properly gives me the /hello.there

however trying it on just / does not group anything. It does not group anything in the string /h as well. I thought it would do it for that because I included a-z in the set to capture.

How can I improve the regex so that it captures / (inclusive) and everything after excluding # and ? while ignoring anything after # and ?

Thank you

when you ask a question about regex, add a tag for the language or the tool you use. — Casimir et Hippolyte
– Casimir et Hippolyte, Commented Dec 8, 2016 at 21:23
Sorry about that.... Alex the regex you gave me does not work on the string "/#test" where it should grab the / only — nelac123
– nelac123, Commented Dec 8, 2016 at 21:25
What if you have a longer path like /hello/there#test or if the string doesn't have a #? — Casimir et Hippolyte
– Casimir et Hippolyte, Commented Dec 8, 2016 at 21:30

Wiktor Stribiżew · Accepted Answer · 2016-12-08 21:28:31Z

2

When you need to match some chars other than some other characters, you should think of negated character classes.

To match any char but # and ? use [^#?]. To match zero or more occurrences, add * after it. Use

/([^#?]*)

See the regex demo

Java demo:

String str = "/hello.there#test";
Pattern ptrn = Pattern.compile("/([^#?]*)");
Matcher matcher = ptrn.matcher(str);
if (matcher.find()) {
    System.out.println(matcher.group());  // => /hello.there
    System.out.println(matcher.group(1)); // => hello.there
}

edited Dec 8, 2016 at 21:28

answered Dec 8, 2016 at 21:25

Wiktor Stribiżew

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Comments

Clare Jang · Accepted Answer · 2016-12-08 21:29:00Z

2

If you want to ignore characters after just # and ?, then exclude those directly.

(/[^#?]*)

In this regex, / is in the group so you can capture it, and [^#?] includes all characters except # and ?.(of course, any characters after those will ignored)

answered Dec 8, 2016 at 21:29

Clare Jang

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2 Comments

Wiktor Stribiżew Over a year ago

Note that capturing the whole pattern is redundant in Java since you always have access to the whole match via Matcher.group() (or Matcher.group(0)).

Clare Jang Over a year ago

@WiktorStribiżew Ah, he used java tag, and I missed it. Thank you for notice.

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