Dataq DI-159, Руководство пользователя

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DI-159 PLC Hardware Manual StickOS
Looping Conditional Statements
Looping conditional statements include the traditional BASIC for-next loop and the more struc-
tured while-endwhile and do-until loops.
The for-next loop statements are of the form:
for variable = expression to expression step expression
statements
next
Where
statements
is one or more program statements and the step
expression
clause is optional
and defaults to 1.
The for-next loop expressions are evaluated only once, on initial entry to the loop. The loop var-
iable is initially set to the value of the first expression. Each time the loop variable is within the
range (inclusive) of the first and second expression, the statements within the loop execute. At
the end of the loop, if the incremented loop variable would still be within the range (inclusive)
of the first and second expression, the loop variable is incremented by the step value, and the
loop repeats again. On exit from the loop, the loop variable is equal to the value it had during
the last iteration of the loop.
The while-endwhile loop statements are of the form:
while
expression
do
statements
endwhile
Where statements is one or more program statements .
Alternately, the string form of this statement is:
while
string relation string
do
statements
endwhile
The while-endwhile loop conditional expression is evaluated on each entry to the loop. If it is
true (non-0), the statements within the loop execute, and the loop repeats again. On exit from
the loop, the conditional expression is false.
The do-until loop statements are of the form:
do
statements
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