$str = 'http://somesite.com/cgi-bin/calendar.pl?some=qstring';

# the typical perlish idiom looks like this
# we are capturing $1 and $2 and assigning them to vars
# all in one line (note this uses m//)
my ( $site, $q_string ) = $str =~ m/^([^\?]+)\?(.*)$/;
print "site: $site\nq string: $q_string\n";

# simple way, just modifying the s/// we had
$str =~ s/^([^\?]+)\?//;
my $capture = $1;
print $capture;
# $str now contains q string