Commodore Plus 4 - Page 47

BASIC Version 3.5 Commands, Functions, and System Variables
Parameters
35
Required
Optional
DO
Commands to be executed by the loop
LOOP
UNTIL conditional formula
WHILE conditional formula
EXIT
UNTIL conditional formula
WHILE conditional formula
Example:
Example:
1. The UNTIL clause usually contains at least one variable that is compared
with a value. The condition of this comparison is checked each time the DO loop
executes. The loop continues repeating until the condition(s) is (are) met. Pro
gram control then passes to the command after the LOOP command.
You can set multiple conditions by linking them with AND or OR (e.g.,
UNTIL X = 5 OR Y > 10).
SO DO UNTIL X = 10
30 PRINT X
40 X = X + 2
50 LOOP
This DO loop executes until X equals 10. When
this condition is met, the loop ends.
2. The WHILE clause usually contains at least one variable that is compared
with a value. The condition of this comparison is checked each time the DO loop
executes. The loop continues repeating while the condition(s) is (are) met. Pro
gram control then passes to the command after the LOOP command.
You can set multiple conditions by linking them with AND or OR (e.g.,
WHILE X = 5 OR Y > 10).
20 DO WHILE X< 10
30 PRHSTT X
40 X = X + 2
50 LOOP
This DO loop executes until X is greater than or
equal to 10. When this condition occurs, the loop
ends.
Notes: The difference between UNTIL and WHILE is that UNTIL conditions
start off not being met; the loop continues until they are. WHILE conditions start
off being met; the loop continues until they are not met.
The conditions in UNTIL and WHILE commands are always either true (met)
or false (not met). If you use more than one condition, join them with AND or
OR. If you use AND, both conditions must be met; if you use OR, only one
condition has to be met.
Both DO and LOOP can have UNTIL conditions or WHILE conditions, but
not both.