6.6 ARCHITECTURE OF `C' PROGRAMS (TOP-DOWN)

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6.6.1 How?

A program should be broken into fundamental parts (using functions for each part) and then assembled using functions. Each function consists of programs written using the previous simpler functions.

A Clear division should be maintained between program levels.

Never use goto's, they are a major source of logic errors. Functions are much easier to use, once written.

Try to isolate machine specific commands (like graphics) into a few functions.

6.6.2 Why?

A top-down design allows modules to be tested as they are completed. It is much easier to find an error in a few lines of code, than in a complete program.

When programs are complete, errors tend to be associated with modules, and are thus much easier to locate.

Updates to programs are much easier, when we only need to change one function.

It is just as easy to change the overall flow of a program, as it is to change a function.

Application of `C' to a CAD Program