Most of us have, at least once, been driven to distraction by the appearance of the much-dreaded "ILLEGAL QUANTITY" error-message, after many hours of typing in reams of DATA numbers. The trouble is that the computer only hints that the error occurs in a READ line, which means poring over the data lines in the somewhat forlorn hope that we spot the mistake.
I have found the following routine a great eye-saver, and I can usually find the error(s) much more quickly. It simply consists of setting up a FOR NEXT loop.
On the line immediately preceding the READ statement, type FOR (X) = i (make sure here you use a number larget than the original "FOR NEXT".
On the line immediately following the original READ line, type: PRINT(X); (and then follow the original READ variables either singly, or, if there are very many, two or three at a time).
On the following line, type: NEXT (X):END
Don't forget END.
On running, this will list all the variables and their corresponding DATA numbers, making the job of weeding out the bugs much easier. The three lines that you may have had to erase in order to add the extra ones will probably take less time than you would have taken to find the bugs by yourself.
14th January 1984
