re: Informix 4gl details

richard, a slight modification to your code (still human readable) gets around this 'problem'. what if my_table has more than 100 rows? DEFINE i INTEGER DEFINE my_arr ARRAY[100] OF RECORD LIKE my_table DECLARE my_cursor CURSOR FOR SELECT * FROM my_table DEFINE MAX_RECS INTEGER LET MAX_RECS = 100 LET i = 1 FOREACH my_cursor INTO my_arr[i].* LET i = i + 1 IF (i = MAX_RECS) THEN display some error message EXIT FOREACH END IF END FOREACH > To all users/developers of Informix 4gl 2.10 or higher: > > My company is still using Informix 1.10, and I am trying to determine if > the following limitation in our compiler is limited to 1.10: > > DEFINE i INTEGER > DEFINE my_arr ARRAY[100] OF RECORD LIKE my_table > DECLARE my_cursor CURSOR FOR > SELECT * FROM my_table> LET i = 1 > FOREACH my_cursor INTO my_arr[i].* > LET i = i + 1 > END FOREACH > > This block of code will produce a run-time error if the table contains > exactly 100 rows, because the Operating System attempts to calculate the > addresses of my_arr[101].* before the database engine can justify ending > the FOREACH loop with the non-existence of another row. Although this > problem is not difficult to work around, it is annoying for 3 reasons: > > 1) The code above is so human-readable that any other solution is > awfully cumbersome by comparison. > > 2) The reference manual is silent about the order of operations in > a FOREACH loop, whereas most reference manuals easily plumb this > level of detail to avoid off-by-one errors by their end-users. > > 3) The unnatural order of operations in the FOREACH loop is > reminiscent of programming languages that eschew short-circuit > evaluation of boolean conditions in favor of evaluating both > sides of an AND or an OR essentially in parallel, thus leading > to convoluted coding. > > Now for the questions: does any version of Informix 4gl later than 1.10 > perform the FOREACH end-of-loop check by querying the database before > calculating the destination memory addresses? > > -Richard H. -- regards, +----------------------------------------------------------------------------+ | . . | | | ... ... | Bob Baskett | | ..... ..... | Software Engineer, DBA | | .. ... .. | Business Systems Integration Group | | . . . | Semiconductor Products Sector | | | Mesa, AZ | | Motorola, Inc. | | |----------------------------------------------------------------------------| | 'connectionLESS IS MORE' -- Data Broker | |----------------------------------------------------------------------------| | Duct tape is like the force. It has a light side, and a dark side, and | | it holds the universe together ... | | -- Carl Zwanzig | +----------------------------------------------------------------------------+