Atari XL User Manual

42
GOTO 100
GOTO 200
GOTO 300
Similarly:
The Ateri XL Handbook
ifN = 1
ifN = 2
ifN = 3
ON P GOSUB 500,200,500,400,100
selects the P'th destination in the list and calls it as
a subroutine. If the value of the variable is greater
than the number of destinations in the list, or if it
is zero, no destination is selected and the program
continues at the next instruction. If the value is
less then zero, the program stops with the error
message (ERROR - 3'. To avoid this, make sure
you only use positive values by testing them first.
For example, instead of:
250 ON NUM GOTO 1000, 2000, 3000
write:
250 TEST=NUM
260 IF TEST<O THEN TEST=O
270 ON TEST GO TO 1000, 2000, 3000
SUMMARY
LOOPS
The loop structure has the form:
FOR V = A TO B STEP C ... NEXT in which the
instructions between the FO R and NEXT
commands are repeated once for each value of V
indicated by the FOR ... STEP command. A, Band
C may be variables or numbers; V must be a
variable. Loops may be nested one within another.

Atari XL Specifications

General

Brand	Atari
Model	XL
Category	Desktop
Language	English