Re: Howto strip 42 from comma separated list using s///

I'd look for commas on both sides and only replace one of them if they were both there:

# updated, thanks to PerlMouse -- not using \b, though!
$str =~ s/(^|,)42(,|$)/$1 && $2/e
[download]

Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

Comment on Re: Howto strip 42 from comma separated list using s/// Download Code

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Re^2: Howto strip 42 from comma separated list using s/// by Perl Mouse (Chaplain) on Nov 03, 2005 at 13:42 UTC
You ought to guard the 42 with `\b`'s on both sides, or it will turn `130,1423,999` into `130,13,999`. `Perl --((8:>*`	[reply]
Re^2: Howto strip 42 from comma separated list using s/// by svenXY (Deacon) on Nov 03, 2005 at 13:34 UTC
Hi, sorry, but just for me to understand: `$1 && $2` [download] means: if both are there, return the latest, in this case $2? Like this: `perl -e'$a=1;$b=2;print ($a && $b)'` [download] Thanks, svenXY	[reply] [d/l] [select]
Re^3: Howto strip 42 from comma separated list using s/// by japhy (Canon) on Nov 03, 2005 at 13:37 UTC
It's a trick, I'll admit. In Perl, && returns the right-hand operand if the left-hand one is true, and the left-hand operand if the left-hand one is false. X && Y returns X if X is false, and Y if X is true (regardless of Y's truth value!). Thus, in my regex, a comma is only inserted if both $1 and $2 are true. $1 && $2 is only true when $1 and $2 have commas in them (otherwise, at least one of them is empty, and thus the empty string is returned). Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply]
Re^2: Howto strip 42 from comma separated list using s/// by ady (Deacon) on Nov 03, 2005 at 13:39 UTC
I'm currently doing this in .NET C# (which you couldn't know), where i can't eval like that, so a regex substitution /$1$2/ would eat both commas, like `"41,42,43" -> "4143"` [download] Any plain vanilla regex to do it ? /allan	[reply] [d/l]