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until loop

summary

    This subchapter looks at until loop.

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stub section

    This subchapter is a stub section. It will be filled in with instructional material later. For now it serves the purpose of a place holder for the order of instruction.

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until loop

    The third major repetition or loop structure is the DO UNTIL loop.

    In the DO UNTIL loop there is a condition test and the loop is repeated over and over again until the condition becomes true.

    The DO UNTIL is actually not an appropriate choice for our avaerage example, but it will work and you are already familiar with this example.

    Initialize;
    BEGIN
        Subtotal := 0;
        Count := 0;
        IF there are no numbers available to average
            THEN REPORT an ERROR and STOP;
    END;
    DO UNTIL there are no more numbers available;
    BEGIN
        Add the next number to the Subtotal;
        Increment (add one to) the Count;
    END;
    Finish;
    BEGIN
        IF count NOT EQUAL zero (0)
            THEN average := subtotal / count;
        ELSE
            Report ERROR;
    END;

    As with the the DO WHILE loop, it is vitally important to make sure that your DO UNTIL loop will eventually end and avoid putting your program into an infinite loop.

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