Hi rodinski,

I'll try to explain that last one:

local $_ = join "\n", @trip;
printf "%15s to %-15s\n", $1, $2  while /^(.*)\n(?=(.*))/gm;
[download]

Let's remove the while for a moment and see what happens:

my $test = "Chicago
Saint Looey
Joplin
OKC
Amarillo
Gallup
Flagstaff
Winona
Kingman
Barstow
San Bernandino
LA" ;

if ( $test =~ /^(.*)\n(?=(.*))/gm ) {
    printf "%15s to %-15s\n", $1, $2 ;
}
__END__ 
        Chicago to Saint Looey
[download]

(.*) = Chicago

\n = enter

(?=pattern) = Look around assertion. It is used to look ahead after the enter without changing the position where the last match ended. This is done so that the last arrival location becomes the depart location in the next search. https://perldoc.perl.org/perlre.html#Extended-Patterns

(.*) = Saint Looey

g = is in this case used to change the position where the last match ended. If you leave it out, you get a never ending loop (it will match the first found text over and over again) edit:See https://perldoc.perl.org/perlrequick.html#More-matching

m = Treat string as multiple lines