Do you mean that the opening parenthesis is optional in the text you are spliting? If so, you can use a '?' quantifier to make the opening parenthesis "zero or one of" but you also have to use a negative look behind to make sure you don't split '(' from 'a)'. I've added the 'x' modifier to the pattern so I can space it out and make it more readable.

knoppix@Microknoppix:~$ perl -E '
> $line = q{(a) Line 1. b) Line 2. (c) Line 32. d) Line 42.};
> @arr  = split m{ (?<! \( ) (?= \(? [a-z] \) ) }x, $line;
> say qq{>$_<} for @arr;'
>(a) Line 1. <
>b) Line 2. <
>(c) Line 32. <
>d) Line 42.<
knoppix@Microknoppix:~$

[download]

I hope this is helpful.

Cheers,

JohnGG

In reply to Re^3: RegEx related line split by johngg
in thread RegEx related line split by dominic01

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