#!/usr/bin/perl

use strict;
use warnings;

# Test cases:
my @strings = ("Joe Dolly", # It should split and print JD.
    "perl.pl",   # It should match on the regular expression and nothing prints.
    "States");    # It should match on the regular expression and nothing prints.

for my $str (@strings) {
    next unless $str =~ /\s/;
    my $out = join '', map { $_ = substr ($_, 0, 1) } split (/\s/, $str);
    print "$out\n";
};