Sharp MZ-800 - Page 76

ON ~ GOSUB
Format ON <numeric expression> GOSUB { <line number >[,<line number >] ...
<label> [,<label>] ...
Abbreviated Format
ON~GOS.
Explanation The ON ~GOSUB statement branches program execution to the subroutine indi-
cated by one of the line numbers following GOSUB, depending on the value of
<numeric expression>. The 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.
Example Let us 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 in turn is called by line 90, Subroutines can be nested to many levels in this
manner.
10 A$=" ENGL "': BS="" MATH ": C$="" FREN ”’
20 D$=" SCI ": E$="" MUS) ": F$=" GYM "
30 G$=" HIST ": H$="" ART “': 1$="' GEOG "
40 J$="" BUS =“: K$="" H RM ": CLS
50 INPUT ‘‘WHAT DAY?"';X$
60 FOR Z=1 TO 7:Y$=MID$("SUNMONTUEWEDTHUFRISAT”, 1 +3#(Z—1),3):
IF Y$=X$ THEN X=Z
70 NEXT Z
80 FOR Y=0 TO 4: PRINT TAB(5+6*Y);Y +1;
90 NEXT Y: PRINT
100 ON X GOSUB 180,120,130,140, 150,160,170
110 PRINT: GOTO 50
120 PRINT ‘MON ‘';A$;B$;D$;G$;K$:RETURN
130 PRINT “* TUE $;E$;H$;H$;D$:RETURN
140 PRINT "WED $;C$;1$;A$;F$:RETURN
150 PRINT "THU '';B$;D$;F$;G$;E$:RETURN
160 PRINT “FRI; ‘AS; D$;1$;C$;C$:RETURN
170 PRINT “‘SAT ‘’;B$;G$;D$;K$:RETURN
180 FOR Y=1 TO 6
190 ON Y GOSUB 120,130,140,150,160,170
200 PRINT:NEXT Y
210 RETURN
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