2. 3. 6. 8
ON~GOSUB
...............................
(abbreviated format:
ON~GOS.)
I Format I
ONe
GOSUB
Lr
1
<,
Lr
2
,
Lr
3
,
..•..
, Lri >
Function
Example
e . . . Numeric variable, array element,
or
expression
Lri . Destination line numbers
This statement branches execution to the subroutine beginning
on
one
of
the
line numbers following
GOSUB, depending
on
the value
of
e.
Operation
of
this
statement is basically
the
same
as
with the
ON~GOTO
statement,
but
all branches
are made to subroutines. Upon return from
the
subroutine, execution resumes
with
the first executable statement following the
ON~GOSUB
statement which
made the call.
Let's
try
using
the
ON~GOSUB
statement in a scheduling program. The
most
important
point
to
note
in the following program
is
that, a subroutine call is made
·
at
line 180, even though line 180 itself
is
part
of
a subroutine (from line 170
to
190) which is called
by
line
90
. Subroutines can be nested to many levels in this
manner.
10
A$=
"
20
D$=
"
30
G$=
"
ENGL
. " :
B$=
"
se
1 " :
E$=
"
HI
ST
" :
H$=
"
MATH
MUS
ART
":
C$=
"
":
F$=
"
":
I$=
"
FREN
GYM
GEOG
40
0$=
"
BUS
"
:K$=
" H
RM
"
:PRINT
"
[!)
"
50
INPUT
"WHAT DAY'? "
;X$
60
FOR
Z=1
TO
7:Y$=MID$C
"S
UNMONTUEWEDTHU
FR
I
SAT
" . 1 +3::!<CZ-1 ),
3)
:
IF
Y$
=
X$
THEN
X
=Z
70
NEXT
Z
80
FOR
Y=0
TO
4:PRINT
TAB
C5
+6::!<Y);Y+1;
90
NE XT
Y:PRINT
100
ON
X
GOSUB
180.120.130.140.150.1·60.170
110
PRINT:GOTO
50
·
120
PRINT
"
MON
";A$;
B$;D$;G$;K$:RETURN
130
PRINT
"
TUE
";
B$;E$;H$;H$;D$:RETURN
140
PRINT
"
WED
" ;
C$; C$;
I$;
A$;
F$
:
RETURN
150
PRINT
"THU "
;B$;D$;F$;G$;E$:RETURN
1
60
PRINT
"
FR
I " ;
A$;
D$;
I$
;
C$;
C$
:
RETURN
170
PRINT
"
SAT
";
B$;G$;D$
;K$:R
ETURN
180
FOR
Y
=1
TO
6
1 9 0
ON
Y
GOSUB
1
20.
1
30.
1
40.
1
50.
1
60.
1 7 0
200
PRINT:NE
XT Y
210
RETURN
------------------
-------------------------------------------------------55
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