sub functionname
{
 my $string_param = shift;
 my $array_ref = shift;
 my @array = @{$array_ref};
 my $other_string_param = shift;

 #-- do edit check here, throw error

 #-- do rest of sub function

}

#-- call as:
sub functionname( $string_param, \@array_param, $other_string_param);