Article: Q58214
Product(s): See article
Version(s): 1.00 1.01 1.02 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S900126-95 B_BasicCom B_GWBasicI docerr | mspl13_basic
Last Modified: 31-JAN-1990
The FILES "filespec" statement prints the names of the files residing
on the specified disk. However, the manual doesn't mention that if the
"filespec" parameter does not describe any current filenames, an error
53 ("File Not Found") is returned. Unless this error is trapped,
program execution is halted.
This information applies to Microsoft QuickBASIC Versions 1.00, 1.01,
1.02, 2.00, 2.01, 3.00, 4.00, 4.00b, and 4.50 for MS-DOS; to Microsoft
BASIC Compiler Versions 6.00 and 6.00b for MS-DOS and MS OS/2; to
Microsoft BASIC Professional Development System (PDS) Version 7.00 for
MS-DOS and MS OS/2; and to Microsoft GW-BASIC Interpreter Versions
3.20, 3.22, and 3.23 for MS-DOS.
When a FILES statement is used to list the files in a specific
directory and the pattern that FILES is searching for does not exist,
an error 53 ("File Not Found") is returned.
If the error is not trapped by the program, the error message "File
Not Found" is displayed in the interpreter environment. In executable
programs, the message displayed is "File Not Found In Module
[Filename] at SEG:OFF," where SEG:OFF represents the segment and the
offset from that segment of code where the error happened.
To avoid halting the program, the program needs only to trap the error
53 that is returned to the program. The program examples below
demonstrate this, assuming that a file named ABC.XYZ does not exist on
the root directory of drive C.
Example for Compiled BASICs -- BASPROG.BAS
------------------------------------------
ON ERROR GOTO ErrorHandle
FILES "c:\abc.xyz"
END
ErrorHandle:
IF ERR = 53 THEN PRINT "Error 53 was trapped. File not found."
RESUME NEXT
You can compile and link BASPROG.BAS as follows in QuickBASIC 4.00,
4.00b, or 4.50, BASIC compiler 6.00 or 6.00b, or BASIC PDS 7.00:
BC /x Basprog;
LINK Basprog;
Use QB /x Basprog in QuickBASIC Versions 2.00, 2.01, 3.00.
Use BASCOM /x Basprog in QuickBASIC Versions 1.00, 1.01, 1.02.
Example for GW-BASIC Interpreter
--------------------------------
10 ON ERROR GOTO 999
20 FILES "c:\abc.xyz"
30 END
999 IF ERR = 53 THEN PRINT "Error 53 was trapped. File not found."
1000 RESUME NEXT