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ON ERROR Statement Programming Example
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ON ERROR Statement Programming Example
The following program gets a file name from the user and displays the
file on the screen. If the file cannot be opened, an error-handling
routine traps the error and starts the program again at the prompt
for the file name.
DEFINT A-Z
' establish the error-handling routine
ON ERROR GOTO ErrorHandler
CLS
' get a file name
INPUT "Enter the file to display: ",filename$
' open the file
OPEN filename$ FOR INPUT AS #1
' display the file on the screen
DO WHILE NOT EOF(1)
LINE INPUT #1, aline$
PRINT aline$
LOOP
END
'
' error handling routine handles only "Bad File Name";
' aborts on any other error
'
CONST BADFILENAME = 53
ErrorHandler:
IF ERR = BADFILENAME THEN
' get another file name
PRINT "File " UCASE$(filename$) " not found."
INPUT "Enter the file to display: ",filename$
RESUME
ELSE
' some other error, so print message and abort
PRINT "Unrecoverable error--"; ERR
ON ERROR GOTO 0
END IF