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STRUCTURED DESIGN

Part 1: An Introduction to Structured Techniques
by George Martin

Start ý Sequence ý Selection ý Iteration/Looping ý Testing ý Nassi-Schneiderman Charts ý Sources and PDF

ITERATION/LOOPING

The third structural element is iteration, or looping. In this situation, the condition is tested, and if it is true, then process F is executed and the test is repeated. If the condition is not true, then the program continues. This is commonly called the while loop (see Figure 4).

Figure 4ýWhen the condition is false, the program continues. This is called a while loop.

A slight variation in the construction of this structure is called the until loop, which can be seen in Figure 5.

Figure 5ýA minor dissimilarity in the construction of Figure 4 is what you see here. This is called an until loop.

Now, letýs look at what we have. I contend that all of your code can be written using the three structures I just defined. You can define more structures, such as a case or switch structure, which may make your design more compact or understandable. There are provisions in most languages for this. BASIC has its case statement, and C has its switch statement. But, you can construct either of those out of the three structures shown in this article.

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