|P is for Practical|
Work-around for variable length look-behind?by pat_mc (Pilgrim)
|on Oct 11, 2010 at 10:19 UTC||Need Help??|
pat_mc has asked for the
wisdom of the Perl Monks concerning the following question:
I have a regex problem today that I thought would be a quickie. I have a file with lines containing two strings separated by a whitespace. I want to make a specific global replacement, say every 'b' in front of an 'a' shall beome 'B', ONLY in the second string.
Clearly s/b(?=a)/B/g won't work because it may also effect a replacement in the first string in the line.
Of course, I could capture the second string in a preceeding match and then operate on it. What I want to achieve, however, is to express this in a single regex.
With variable length look-behind unsupported by the Perl version I use (5.8 something) I am at a loss.
Can you please help?
Cheers and thanks in advance for your advise -