Five Programming Steps
Every program, no matter how complex, can be reduced to five fundamental steps. These steps are
Let's examine each of these steps in greater detail.
The initialization step is the first step you should think about when you design a program. The initialization step includes everything the program should do
the program begins interacting with the user. At first, the concept of doing things before interacting with the
For example, we've all used Microsoft's Word, Excel, or similar programs. With such programs, you know that you can click on the File menu option and see a list of the files you worked with recently near the bottom of the menu. They didn't get there by magic. The program probably read the list of recently used files from a disk data file and appended that list to the File menu. Because this list is read before the program displays anything to the user, it
Anther common task that's often relegated to the Initialization step includes reading setup files. Such setup files might include information about the
In your own programs, you need to think about what type of information your program must have before it can do its job. If your design requires any type of setup or pre-program information, the Initialization step is probably where you should handle it.
The Input step is exactly what you expect it to be. It's the step that collects whatever inputs the program needs to accomplish its task. In most cases, if you think about what the program is supposed to accomplish, defining the list of inputs is
In other cases, however, you really need to think about what inputs should be
Where the inputs come from is a design decision. Setup files are great and should be used whenever possible. Obviously, other input information cannot be known until the user types it in, as in our loan interest example. In such situations, you'll likely use text boxes to collect the information from the user for use in the program. Because the user must interact with these text boxes to supply program information, the way you lay out the text box, labels,
Entire books have been written on how to design an effective user interface. There's no way that I can do the topic
The Processing step involves acting on the inputs to produce the result desired from the program. In our loan example, the program would accept the inputs (that is, the loan amount, interest rate, and
Note that the Processing step usually does
display anything on the screen. Its sole purpose is to act on the data to generate a result. There's one notable exception to this rule, however. If you know beforehand that the Processing step is going to take a long time, it's usually a good idea to provide some feedback to the user that the program is still running. We've all run programs where a progress bar shows us what percentage of the task at hand has been completed. Another common example is programs that provide an estimate of the time remaining before completion. A lot of Web-based program use this approach. These situations need some form of feedback so that the user
In a sense, this is the whole purpose of the program in the first place: to give the users an answer to whatever problem it was they wanted
Other programs, however, are much more complex. Perhaps you've run programs that read your name, address, phone number, and perhaps a half-
The important thing to note in the Output step is that because you're displaying results to the user, it's also part of the user interface. You saw earlier that the Input step was an element in the user interface because it collected data from the user. In the Output step, the user interface
The Cleanup step is used to gracefully shut down a program after it has completed its task. You can think of this step as the
The Cleanup step is often associated with closing disk data files, including setup and database files. Some programs track how long a user ran a program and
Another type of log file is called an
error log file.
The purpose of an error log file is to record information about any errors that were
The actual tasks that are performed in the Cleanup step depend on the needs of the program itself. However, chances are that if something needs to be done in the Initialization step, some form of matching
Five Steps for Every Program?
Does every program require all five programming steps? No. As you'll see in the
As you gain experience in writing programs, you'll develop a knack for knowing which programs need all five programming steps and which don't. However, you should always approach a programming design problem under the assumption that all five steps are needed. It's always easier to throw away steps later in the design than it is to squeeze them in once the design is well underway.