Regular expressions in Groovy - extract part before first underscore only

Question

Given is a string variable elementOne.

def elemenOne = 'AB_CD_EF_GH'

The challenge is to extract only the 'AB', the first part of its value, only that which precedes the first underscore symbol (counted from the left to right).

I have written a code:

def elementTwo = (element_one =~ /^.*(?=(_))/)[0][0]

but it extracts 'AB_CD_EF' instead of only 'AB'.

How should I modify my code, in order to extract only 'AB' part from 'AB_CD_EF_GH'?

Thank you!

Try `^[^_]+(?=_)` See https://regex101.com/r/6aPa1O/1 – The fourth bird Jan 15 '20 at 16:22 — The fourth bird, Jan 15 '20 at 16:22
`.*` is greedy, use a lazy one, `.*?` – Wiktor Stribiżew Jan 15 '20 at 19:07 — Wiktor Stribiżew, Jan 15 '20 at 19:07

score 0 · Answer 1 · answered Jan 15 '20 at 16:26

0

You don't need to use a regexp for this... Which can end up with code that's easier to read later on...

Here's some techniques... The last one is a regexp method

def elemenOne = 'AB_CD_EF_GH'

assert 'AB' == elemenOne.takeWhile { it != '_' }
assert 'AB' == elemenOne.split('_').head()
assert 'AB' == (elemenOne =~ '([^_]+)_.*')[0][1]

answered Jan 15 '20 at 16:26

tim_yates

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Thank you very very very much! – youtube2019 Jan 16 '20 at 08:50

score 0 · Answer 2 · answered Jan 15 '20 at 18:44

There are details missing that might affect your decision about how best to do this but for a starting point, this will evaluate to the result you are looking for...

def inputString = 'AB_CD_EF_GH'

def match = (inputString =~ /^[^_]+(?=_)/)[0]

println match

Regular expressions in Groovy - extract part before first underscore only

2 Answers2