Need regex for returning string with portion removed

Question

I'm struggling to figure out the proper regex for this.

I have a string that looks something like this: here-is.my.string

I need to return a string that removes everything starting with the dash up to (but not including) the first dot. here.my.string

Thanks.

If you're struggling with something, you should show your attempts. — the Tin Man
– the Tin Man, Commented Dec 4, 2014 at 17:16

Cristian Lupascu · Accepted Answer · 2014-12-04 17:16:29Z

4

Do this:

puts 'here-is.my.string'.sub(/-[^.]+(?=\.)/, '')

The trick here is the positive look-ahead ((?=\.)), which requires that there is a dot following the match, but does not consider it a part of the match.

Edit:

As Avinash Raj and mudasobwa pointed out in the comments, it's enough to require a greedy sequence of characters that are not dots. This works just as well:

puts 'here-is.my.string'.sub(/-[^.]+/, '')

edited Dec 4, 2014 at 17:16

answered Dec 4, 2014 at 16:18

Cristian Lupascu

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2 Comments

Avinash Raj Over a year ago

i think you don't need a lookahead.

Aleksei Matiushkin Over a year ago

While this works perfectly, the positive look-ahead here is an overkill. /-[^.]+/.

the Tin Man · Accepted Answer · 2014-12-04 17:17:56Z

2

Ruby has a bajillion ways to do it. Here's a very simple way:

str = 'here-is.my.string'
str[/-[^.]+/] = ''
str # => "here.my.string"

It just finds the match and assigns '' to it.

answered Dec 4, 2014 at 17:17

the Tin Man

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