Re: count repeatation

There are more than one way to do this.

#!/usr/bin/perl

use strict;

my $string = 'ab23cdefgXX(3A5)XXhijkl23mnXX(3)XXopq432rsXX(450b)XXtuv'
+;
my @counts = split( "XX", $string );

print $#counts;
[download]

Comment on Re: count repeatation Download Code

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Re^2: count repeatation by JavaFan (Canon) on Aug 19, 2009 at 16:14 UTC
That doesn't always provide the correct results. `my $string = "XXXX"; my @count = split( "XX", $string ); print $#count; # Prints -1` [download] One could fix that by giving split third argument. But it doesn't scale to generic patterns. Suppose you want to count how after characters are repeated (so, count not only "XX", but also "AA", "22", "--", etc). A pattern `/(.)\1/` matches that, but `my $string = "XXYY"; my @count = split( /(.)\1/, $string, -1 ); print $#count; # Prints 4, not 2.` [download] The reason is that if the pattern in contains capturing parenthesis, split returns what's captured in the parens as well.	[reply] [d/l] [select]

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Re^2: count repeatation
by JavaFan (Canon) on Aug 19, 2009 at 16:14 UTC

my $string = "XXXX";
my @count = split( "XX", $string );
print $#count;   # Prints -1
[download]

But it doesn't scale to generic patterns. Suppose you want to count how after characters are repeated (so, count not only "XX", but also "AA", "22", "--", etc). A pattern /(.)\1/ matches that, but

my $string = "XXYY";
my @count = split( /(.)\1/, $string, -1 );
print $#count;   # Prints 4, not 2.
[download]

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