sub display_error {
my $html_title = $_[0];
my $error = $_[1];
print $cgi->start_html(-title=>"Error: $html_title").
      $cgi->h3($error).
      $cgi-end_html();
}

##</code><code>##

display_error("User already exists","Sorry, user $add_user already exists, founded line $found.");

##</code><code>##

Software error:
Undefined subroutine &main::end_html called at C:/Program Files/Apache Group/Apache2/htdocs/login.pl line 231.