until loop (original) (raw)

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summary

This subchapter looks at until loop.

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.

Stanford C essentials

Stanford CS Education Library This [the following paragraph and code example] is document #101, Essential C, in the Stanford CS Education Library. This and other educational materials are available for free at http://cslibrary.stanford.edu/. This article is free to be used, reproduced, excerpted, retransmitted, or sold so long as this notice is clearly reproduced at its beginning. Copyright 1996-2003, Nick Parlante, nick.parlante@cs.stanford.edu.

Do-While Loop

[NOTE; Although the C language uses the word “while” , this is actually an UNTIL loop.]

Like a while, but with the test condition at the bottom of the loop. The loop body will always execute at least once. The do-while is an unpopular area of the language, most everyone tries to use the straight while if at all possible.

do {

} while ()

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Create your own copy from the original source code/ (presented for learning programming).

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