To follow up, here's some code indicating what split /\C/ does:

#!perl -w
use strict;
while (<DATA>) {
    chomp;
    warn "input line is '$_'\n";
    my @t = split /\C/, $_; 
    warn "split to [n=@{[ scalar @t ]}]: '@t'\n";
}

# input line is '31415926'
# split to [n=0]: ''
# input line is '12345678'
# split to [n=0]: ''

__DATA__
31415926
12345678
[download]