| .ERROR Statement Programming Example. |
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| ERROR Statement Programming Example |
|
| This example uses an ERROR statement in an error-handling |
| routine, Handler, to trap a user input error. |
| |
| Tip: You must supply a text file when you run this example. |
| Use a text file you have already created, create a file |
| with a text editor, or specify the README.DOC text file. |
| |
| ON ERROR GOTO Handler |
| OpenFile: |
| INPUT "Name of file to update"; FileSpec$ |
| IF FileSpec$ = "" THEN END |
| OPEN FileSpec$ FOR INPUT AS #1 |
| PRINT "The first five lines of "; FILESPEC$;" are:" : PRINT |
| FOR I = 1 TO 5 |
| LINE INPUT #1, Temp$ |
| PRINT Temp$ |
| NEXT |
| PRINT : INPUT "Is this the correct file"; R$ |
| 'Define error 200. |
| IF LEFT$(R$,1) <> "y" THEN ERROR 200 |
| END |
| |
| Handler: 'Error-handling routine. |
| Number = ERR |
| 'If program generates run-time error for "file not found," |
| 'a special message is printed and the user is prompted to |
| 'enter a new file specification or end the program. |
| IF Number = 53 THEN |
| CLOSE #1 |
| PRINT "File not in this directory" |
| PRINT "Enter new file spec ([d:]\\xxx\\...\\xxx) or" |
| PRINT "press to end program" |
| RESUME OpenFile |
| ELSEIF Number = 200 THEN 'User entered "n" |
| CLOSE #1 |
| RESUME OpenFile |
| ELSE |
| ERROR Number 'Error other than 53 or 200. |
| ON ERROR GOTO 0 'Print message, disable error |
| END IF 'handling, and stop program. |
| |
