my ($first,$last) = ("John", "Doe");

# interpolate into a string:
print "$first $last\n";

# put a literal space between them in list context:
print $first, ' ', $last,"\n";

# join a list of values with space. This works with arrays, too
print join(' ', ($first, $last)),"\n";

# $, is the output field separator
{
    local $,=' ';
    # prints "John Doe \n", note the space at the end!
    print $first, $last, "\n";
}