Commodore Plus 4 - Page 85

Another example, with a negative STEP
10 PRINT "COUNTDOWN..."
20 FOR J = 10 TO 0 STEP 1
30 PRINT "WE ARE AT";J
— 40 NEXTJ
50 PRINT "WE HAVE LIFT-OFF AT" ; J
Statement Name: DO UNTIL/WHILE... LOOP UNTIL/WHILE
— Format: DO UNTIL [conditionl WHILE [condition]
some BASIC statements
I EXIT]
— LOOP UNTIL {condition] WHILE [condition]
The DO, LOOP statement combination is another way to create a
loop. This statement combination is very powerful and versatile. The
DO.'LOOP method of loops is a common technique of structured
programming languages. In this chapter we'll discuss just a few
possible uses.
If you want to create an infinite loop, just start a section of program
lines with DO, and end it with a LOOP statement, like this
100 DO: PRINT "GOING UP"
110 LOOP
Press the STOP key to end the program.
A more useful form is to combine the DO; LOOP with the UNTIL
statement. The loop will run continually unless the condition for
UNTIL happens.
— 100 DO: INPUT "DO YOU LIKE YOUR COMPUTER'1 ;A$
110 LOOP UNTIL A$="YES"
120 PRINT "THANK YOU"
For the other ways you can use the DO; LOOP, seethe BASIC
— Encyclopedia at the end of this book
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