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GeoBASIC Reference Manual 2.GeoBasic Constructs
2-40 TPS1100-Version 1.30
•
If control is transferred from outside to a label inside a structured statement,
this may have undefined consequences, e.g. in case of a
FOR
-statement.
Such transfers must be avoided.
Note
ERROR
,
GOTO
, and
RESUME
are not reserved words, but
ON
is.
Examples:
♦
First, a simple example. An error will be ignored and passed to the caller.
SUB ABC
ON ERROR RESUME NEXT
...
'statements
CALL ExternalSystemRoutine (..)
...
'statements
END ABC
♦
The next example shows an external system routine call. If an error occurs,
then the statements in
ErrLab
may make some changes and try the execution
again. If the error occurs a second time, the program aborts immediately.
SUB Dispatch
LABEL ErrLab
...
'statements
ON ERROR GOTO ErrLab
CALL ExternalSystemRoutine (..)
EXIT
ErrLab:
... 'make changes
ON ERROR GOTO 0
'abort next time
CALL ExternalSystemRoutine (..)
...
'statements
END Dispatch