Re^2: Counting text with ligatures

[Corion]

At least on Perl 5.14 and Perl 5.20, this doesn't work (and I don't understand why):

use strict;
use charnames ":full";

my $string = "\N{LATIN SMALL LIGATURE FFI}";
print "length: ",length($string),"\n"; # wrong way

my $len = () = $string=~/\X/g;
print "len: $len\n";

my @graphs  = split /\X\K(?=\X)/, $string;
print "graphs: ", 0+@graphs, "\n";

__END__

length: 1
len: 1
graphs: 1

Is maybe our understanding of graphemes different from the separate letters of the ligatures?

[haukex]

My initial understanding of the OP's question was that it has to do with Unicode being able to represent the same user-visible character in multiple different ways, like with combining characters. That is, the two strings "\N{LATIN SMALL LETTER E WITH ACUTE}" and "e\N{COMBINING ACUTE ACCENT}" report different lengths (1 resp. 2), even though on the screen they both look like "é" (one "grapheme"), and so users would expect a "length" of each string to be reported as 1. I may have misunderstood the OP's question though - if you have the strings "ffi" vs. "ffi", and you want to know if they have the same length and/or are equal, then perhaps what the OP is looking for is Unicode equivalence (normalization).

use Unicode::Normalize;
use Data::Dump;
dd NFD("\N{LATIN SMALL LETTER E WITH ACUTE}"),
   NFD("e\N{COMBINING ACUTE ACCENT}");
dd NFC("\N{LATIN SMALL LETTER E WITH ACUTE}"),
   NFC("e\N{COMBINING ACUTE ACCENT}");
dd NFKD("\N{LATIN SMALL LIGATURE FFI}");
__END__
("e\x{301}", "e\x{301}")
("\xE9", "\xE9")
"ffi"

Updated example code to include the "é" examples.