Commodore Plus 4 - Page 76

64 The BASIC Language
ON ... GOTO Abbr. on/gO
ON number GOTO line number, line number, etc.
Branches the program to one of a list of line numbers. The selection is based on
the condition of the ON value and the position of the line numbers in the GOTO
list.
Each time ON... GOTO executes, only one of the line numbers in the GOTO
list is used. When the ON value equals 1, the computer goes to the first line
number in the GOTO list. When the ON value equals 2, the computer goes to the
second line number in the GOTO list, and so on.
ON ... GOTO is similar to IF ... GOTO, but ON lets you include a series of
GOTO lines while IF lets you include only one.
Parameters: ON value GOTO line number list
1. The ON value can be a variable or a calculation. It cannot be a negative
number. If it is equal to zero or a number that is greater than the number of line
numbers in the GOTO command, no GOTO is executed. If it is not a whole
number, its truncated value is used. For example, if there are four line numbers in
the GOTO command (e.g., ON number GOTO 40,70,100,130), the number must
be greater than or equal to 1 and less than 5 for a GOTO to be executed.
2. The ON value selects a line number from the GOTO list based on its relative
position in the GOTO list.
Example: 10 TRAP 130
20 IITPUT "WHAT YEAR (1985-1994)";Y
30 PRIFT "1TEW YEAR'S DAY PALLS ON ";
40 0NY-1984G0T0 70,80,90,100,120,60,70,80,100,120
50 PRINT^IWVALID INPUT":GOT020
60 PRINT"MONDAY":END
70 PRIWT"TUESDAY":END
80 PRINT"WEDNESDAY":END
90 PRINT"THURSDAY":END
100 PRINT"PRIDAY":END
110 PRINT"SATURDAY":END
120 PRDOT"SUNDAY":END
130 RESUME 50
OPEN Abbr. oP
OPEN file number, device, secondary address, file name
Opens access to a peripheral device or to a tape or disk file. Devices and files
must be OPENed before you can issue other commands (such as INPUT# or
PRINT#) to them. You do not have to use OPEN before you load or save a
program.