2.10.3 IF ERL
I Format I
IF
relational expression using
ERL
THEN Lr
Function
Example
IF
relational expression using
ERL
THEN statement
IF
relational expression using
ERL
GOTO Lr
Lr
....
Destination line number
This statement branches execution to the routine starting
at
line Lr or executes the
statement
following THEN when
the
result
of
<relational expression using
ERL>
is true.
ERL
is a special function which returns
the
line number
at
which an error occurred.
The following statement causes execution to branch
to
line 1300 if an error has
occurred
on
line 250.
1010
IF
ERL
= 250 THEN 1300
The following statement returns control to line 520 in the main routine
if
the
error
number is 43 and the error line number
is
other
then 450.
1020
IF
(ERN=
43) *
(ERL
< > 450) THEN RESUME 520
2.1
0.4 RESUME
........................................................
(Abbreviated format: RESU.)
I Format I RESUME
<NEXT>
RESUME Lr
Function
I Discussion I
2.10.5 SIZE
Format
Function
Lr
....
Line number
or
0
This statement returns control
to
the main routine from an error processing routine.
The system holds
the
number
of
the line
on
which the error occurred in memory
and returns program execution to
that
line
or
to
another specified line after
the
error is corrected.
The
RESUME statement may be used in any
of
the following four forms:
RESUME
·········· ··· ·
··
··
··
Returns
to
the error line.
RESUME
NE
X T ···
··
Returns to
the
line following the error line.
RESUME
L r
··
········· Returns to line Lr.
RESUME
0 · · · · · · · · · · · · · · Returns to the beginning
of
the
main routine.
If
the
RESUME
is
encountered when no error has occurred, error
21
(RESUME
ERROR) occurs.
If
the
RESUME cannot be executed, error 20 (CAN'T RESUME ERROR) occurs.
PRINT SIZE
This
is
a special function which returns the number
of
bytes in memory which can
be
used for storage
of
BASIC programs.
For
example, PRINT SIZE displays
the
number
of
free bytes
of
memory area.
------------------------------------------------------------------------97
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