use strict;
use warnings;

my @phrases = ("hi there",
               " this and that ",
               "   and the other thing",
               "blah blah blah  ",
               "one two there",
               "    four five six ");
               
@phrases = map { trim($_) } @phrases;
print join("\n", @phrases);

sub trim {
    my $string = shift;
    $string =~ s/^\s+//;  #trim leading space
    $string =~ s/\s+$//;  #trim trailing space
    return $string;
}