Re: how to search and replace the match with specific number of times in a string

If replacing doesn't create a new possible match, you could do:

$string =~ s/a/i/ for 1 .. $N;
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Or, in the rare case searching from the beginning over and over again is expensive, or if a replace could create a new match:

my $count = 0;
$string =~ s/a(??{++ $count <= $N ? "(*ACCEPT)" : "(*FAIL)"})/i/g;
# Use '""' instead of '(*ACCEPT)' and '(?!)' instead of '(*FAIL)' on o
+ld Perls.
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Re^2: how to search and replace the match with specific number of times in a string by AnomalousMonk (Archbishop) on Jan 29, 2010 at 18:00 UTC
Note that there is a warning (at least as of the current documentation) that the `(ACCEPT)` backtracking control verb is "... highly experimental [and] is not recommended for production code." A slightly different take: `>perl -wMstrict -le "my $N = 3; my $string = 'XXXXXaXXbXXXc'; $string =~ s{ X (?(?{ $N and $N-- }) \| (FAIL)) }{Xy}xmsg; print $string; " XyXyXyXXaXXbXXXc` [download] See Special Backtracking Control Verbs in perlre.	[reply] [d/l] [select]

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Re^2: how to search and replace the match with specific number of times in a string
by AnomalousMonk (Archbishop) on Jan 29, 2010 at 18:00 UTC

Note that there is a warning (at least as of the current documentation) that the (*ACCEPT) backtracking control verb is "... highly experimental [and] is not recommended for production code."

A slightly different take:

>perl -wMstrict -le
"my $N = 3;
 my $string = 'XXXXXaXXbXXXc';
 $string =~ s{ X (?(?{ $N and $N-- }) | (*FAIL)) }{Xy}xmsg;
 print $string;
"
XyXyXyXXaXXbXXXc
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See Special Backtracking Control Verbs in perlre.

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