RESUME¶

Purpose¶

To continue program execution after an error recovery procedure has been performed.

Syntax¶

RESUME has three forms:

RESUME                  ' Retry the statement that caused the error
RESUME NEXT             ' Continue at the statement after the error
RESUME <line number>    ' Continue at a specific line number

Remarks¶

Form 1: RESUME¶

Execution resumes at the statement that caused the error.

Use this form when: - You've fixed the condition that caused the error - You want to retry the same operation - Example: User entered invalid data, now it's corrected

Form 2: RESUME NEXT¶

Execution resumes at the statement immediately following the one that caused the error.

Use this form when: - You want to skip the statement that caused the error - The error is expected and can be safely ignored - Example: Optional file operation failed, continue anyway

Form 3: RESUME ¶

Execution resumes at the specified line number.

Use this form when: - You want to continue at a different location - Error recovery requires jumping to a specific section - Example: Fatal error, jump to cleanup routine

Important Notes¶

RESUME can only be used inside an error handler (set up with ON ERROR GOTO)
Using RESUME outside an error handler causes "RESUME without error" error
After RESUME executes, the error handler is still active for future errors
Use ON ERROR GOTO 0 to disable error trapping

Example¶

Example 1: RESUME - Retry After Fixing Error¶

10 ON ERROR GOTO 1000
20 PRINT "Enter a non-zero number:"
30 INPUT A
40 X = 100 / A
50 PRINT "Result: "; X
60 END

1000 REM Error handler
1010 PRINT "Error: Division by zero"
1020 PRINT "Please enter a non-zero number:"
1030 INPUT A
1040 RESUME

Output:

Enter a non-zero number:
? 0
Error: Division by zero
Please enter a non-zero number:
? 5
Result: 20

Explanation: - Line 40 causes division by zero error - Error handler gets new value for A - RESUME (line 1040) retries line 40 with new value

Example 2: RESUME NEXT - Skip Error and Continue¶

10 ON ERROR GOTO 1000
20 OPEN "I", #1, "DATA.TXT"
30 PRINT "File opened successfully"
40 CLOSE #1
50 PRINT "Program continues"
60 END

1000 REM Error handler
1010 PRINT "Warning: Could not open file"
1020 PRINT "Continuing without file..."
1030 RESUME NEXT

Output (if file doesn't exist):

Warning: Could not open file
Continuing without file...
Program continues

Explanation: - Line 20 fails (file not found) - Error handler prints warning - RESUME NEXT (line 1030) skips to line 30 - Program continues

Example 3: RESUME - Jump to Specific Location¶

10 ON ERROR GOTO 1000
20 PRINT "Opening files..."
30 OPEN "I", #1, "INPUT.DAT"
40 OPEN "O", #2, "OUTPUT.DAT"
50 PRINT "Processing..."
60 REM ... processing code ...
70 CLOSE #1, #2
80 END

1000 REM Error handler
1010 PRINT "Error "; ERR; " at line "; ERL
1020 IF ERR = 53 THEN PRINT "File not found"
1030 PRINT "Closing files and exiting..."
1040 RESUME 2000

2000 REM Cleanup routine
2010 CLOSE
2020 PRINT "Program terminated"
2030 END

Explanation: - Error in file operations - Handler identifies error type - RESUME 2000 jumps to cleanup routine - All files closed, program exits cleanly

Example 4: Using ERR and ERL with RESUME¶

10 ON ERROR GOTO 1000
20 FOR I = 1 TO 5
30   PRINT "Attempting operation "; I
40   X = 100 / (I - 3)
50   PRINT "Success: "; X
60 NEXT I
70 END

1000 REM Error handler
1010 PRINT "Error "; ERR; " at line "; ERL
1020 IF ERR = 11 THEN PRINT "Division by zero - skipping"
1030 RESUME NEXT

Output:

Attempting operation  1
Success:  -50
Attempting operation  2
Success:  -100
Attempting operation  3
Error  11  at line  40
Division by zero - skipping
Attempting operation  4
Success:  100
Attempting operation  5
Success:  50

Explanation: - Loop processes 5 operations - Operation 3 causes division by zero (I-3 = 0) - ERR = 11 (division by zero error code) - ERL = 40 (line where error occurred) - RESUME NEXT skips the error, continues loop

Example 5: Multiple Error Types¶

10 ON ERROR GOTO 1000
20 INPUT "Enter line number to jump to: ", L
30 GOTO L
40 END

1000 REM Error handler
1010 PRINT "Error "; ERR; " occurred"
1020 IF ERR = 8 THEN PRINT "Line does not exist": RESUME 20
1030 IF ERR = 6 THEN PRINT "Overflow": RESUME 20
1040 PRINT "Unknown error": END

Explanation: - Handles multiple error types - ERR = 8: Undefined line number - ERR = 6: Overflow - Different RESUME behavior based on error type

Error Codes Reference¶

Common error codes used with RESUME:

ERR	Error
2	Syntax error
6	Overflow
11	Division by zero
13	Type mismatch
53	File not found
55	File already open
57	Device I/O error
62	Input past end of file

Testing RESUME¶

Verified behavior against real MBASIC 5.21: - ✅ RESUME retries error line - ✅ RESUME NEXT skips to next statement - ✅ RESUME jumps to specified line - ✅ ERR and ERL variables work correctly - ✅ "RESUME without error" when used outside error handler