Re^2: Regex Question

You were bitten by negative-over-or-logic. The left side of the | will match what the right side is intended to skip. It has to be something like

$field =~ s/
  (?<!C(?=.O))   # Look back a character and make sure it's not C-some
+thing-O from there
  (?<!\d(?=.\d)) # Make sure it's also not a digit-something-digit
  (?:\\|\/)      # The something is a slash or backslash
/ & /xgi;
[download]

Caution: Contents may have been coded under pressure.

Comment on Re^2: Regex Question Download Code

Replies are listed 'Best First'.
Re^3: Regex Question by Aristotle (Chancellor) on Nov 15, 2005 at 19:58 UTC
~~That won’t match the exact same things. The OP’s regex will replace the slash in `"/2"` or in `"1/"`, yours won’t. Not sure if this is part of the spec, but it’s something to be aware of.~~ Meh. That’s it, I’m going back to bed. Makeshifts last the longest.	[reply] [d/l] [select]
Re^4: Regex Question by Roy Johnson (Monsignor) on Nov 15, 2005 at 20:23 UTC
Mine does replace the slash when it has a digit on only one side. The logic is that the slash is replaced unless there is a digit on both sides. It is the OP's logic that will not replace a slash with a digit on either side. `for my $field ( map $_, 'C/O', '2/4', 'C/2', 'd/l', '2/', '/2') { print "$field..."; $field =~ s/ (?<!C(?=.O)) # Look back a character and make sure it's not C-so +mething-O from there (?<!\d(?=.\d)) # Make sure it's also not a digit-something-digit (?:\\\|\/) # The something is a slash or backslash / & /xgi; print "$field\n"; }` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re^4: Regex Question by shemp (Deacon) on Nov 15, 2005 at 20:07 UTC
Yes, that would comply with my specification of the problem. If there is only a digit on one side, replace the slash with an ampersand. I use the most powerful debugger available: print!	[reply]