/*
 * call-seq:
 *    res.getlength( tup_num, field_num ) -> Fixnum
 *
 * Returns the (String) length of the field in bytes.
 *
 * Equivalent to <tt>res.value(<i>tup_num</i>,<i>field_num</i>).length</tt>.
 */
static VALUE
pgresult_getlength(VALUE self, VALUE tup_num, VALUE field_num)
{
        PGresult *result;
        int i = NUM2INT(tup_num);
        int j = NUM2INT(field_num);

        result = get_pgresult(self);
        if (i < 0 || i >= PQntuples(result)) {
                rb_raise(rb_eArgError,"invalid tuple number %d", i);
        }
        if (j < 0 || j >= PQnfields(result)) {
                rb_raise(rb_eArgError,"invalid field number %d", j);
        }
        return INT2FIX(PQgetlength(result, i, j));
}