In Unicode a grapheme is a logical character that might be represented as several distinct, combined Unicode characters.
For example, the latin small letter ç (c with cedilla) can be written as the single character U+00E7, or the juxtaposition of simple letter c (U+0063) and U+0327, COMBINING CEDILLA:
$ perl -CS -wE 'say chr 0xe7, " ", "c", chr 0x327'
ç ç
The latter has a length of 2:
$ perl -CS -wE 'say length for "\xe7", "c\x{327}"'
1
2
This is expected, but can lead to unexpected results when you meant to work with graphemes but actually work with characters.
There is one Perl construct that understands graphemes: the regular
expression atom \X, which matches a single grapheme, eventually
made out of several characters. This way you can extract single
graphemes from a string:
$ perl -CS -wE 'say length, " $_" for "\xe7c\x{327}c" =~ /\X/g'
1 ç
2 ç
1 c
Also, Perl 5.22.0 introduces a new regular expression assertion, \b{gcb}
(for "grapheme cluster boundary"), that matches only between graphemes.