I want to match patterns of alternating lowercase characters.
ababababa -> match
I tried this
([a-z][a-z])+[a-z]
but this would be a match too
ababxyaba
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cmplx96
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"Alternating" or just "uneven number" of chars? If the latter, enclose the pattern with `^` and `$` anchors. – Wiktor Stribiżew Aug 04 '17 at 10:28
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what do you mean by alternating lowercase characters ? – marvel308 Aug 04 '17 at 10:31
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a string containing an alternation of two of the same characters - > xyxyxyxy but not xyxyxyabxyxy – cmplx96 Aug 04 '17 at 10:37
1 Answers
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You can use this regex with 2 back-reference to match alternating lowercase letters:
^([a-z])(?!\1)([a-z])(?:\1\2)*\1?$
RegEx Breakup:
^: Start([a-z]): Match first letter in capturing group #1(?!\1): Lookahead to make sure we don't match same letter again([a-z]): Match second letter in capturing group #3(?:\1\2)*: Match zero or more pairs of first and second letter\1?: Match optional first letter before end$: End
anubhava
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