Peters Flexible RenAmiNg Kit (PFrank)

bitmonger · Joined: 03 Oct 2007 Posts: 3

I've run into a minor problem where I have two captured groups to use in a replacement, and I wanted to place a zero between them.
e.g the replacement should be a zero between \1 and \2 which ends up \10\2. I think you can see the problem - PFrank interprets this as group 10 followed by group 2 (although there are only 2 captured groups), and complains and stops. I tried substituting hex \x30 for the space - i.e. \1\x30\2, and also tried quoting the zero, but no luck. I worked around it by first replacing with a space followed by the zero thusly: \1 0\2 and then did a second replace of the space with nothing. I don't think this is unique to PFrank, just a fluky combination in a regex. Am I overlooking something obvious - Is there any way to define the zero in this position so it would be a single replace?

Cheers
BM

admin · Site Admin Joined: 09 Mar 2007 Posts: 448 Location: Canada

You need to use the non-ambiguous notation:

\g<1>0\2

or

\g<1>0\g<2>

The \g notation is used for cases like the one you just described to remove any ambiguity in back references.

Great question!

Peter.