Atari 800

Intr oduction to Atar i BASIC 67
The loop will continue to be executed until r\ atta ins a value
greater than
20 . When this occu rs , the state ment following the
NEXT statement will be executed.
In our preceding example, A is known as an index variable. If the
optional keyword STEP is not inc luded w ith the FOR statement,
the
inde x variable will be incr emented by 1 every time the NEXT
statement is executed.
STEP can be included at the end of a FOR stateme nt to change
the value by
which th e inde x variable is incr eme nted . The
integer appearing after STEP is the new increment. For example,
if our preceding exa mple were changed as follows ,
100 FOR A = 1 TO 20 STEP 2
200 X = A A 2
300 PRINT X
400 NEXT A
500 END
the
inde x variable A would be increment ed by 2 every time the
NEXT stateme nt was executed.
Nested Loops
One loop can be placed inside of another loop . The innermost
loop is known as a nested loop. The following program contains
a nested
loop .
100 P = 1000
200 FOR Y = 1 TO 10
300 FOR Q = 1 TO 4
400 P = P + P * .02
500 NEXT Q
600 NEXT Y
650 PRINT P
700 END
Our preceding example is us ed to calculate the value of 1000
after 10 years with an interest rate of 8% compounded quarterly.
On e error that you should take care to avoid when us ing nested