Tools of Flowcharting
Next we will take a look at the tools used in flowcharting. These tools are the fundamental symbols, graphic symbols, flowcharting template, and the flowcharting worksheet.
FUNDAMENTAL SYMBOLS. - To construct a flowchart, you must know the symbols and their related meanings. They are standard for the military, as directed by Department of the Navy Automated Data Systems Documentation Standards, SECNAVINST 5233.
Symbols are used to represent functions. These fundamental functions are processing, decision, input/output, terminal, flow lines, and connector symbol. All flowcharts may be initially constructed using only these fundamental symbols as a rough outline to work from. Each symbol corresponds to one of the functions of a computer and specifies the instruction(s) to be performed by the computer. The contents of these symbols are called statements. Samples of these fundamental symbols, definitions, examples, and explanations of their uses are shown in figure 3-3.
Figure 3-3. - Fundamental flowcharting symbols.
GRAPHIC SYMBOLS. - Within a flowchart, graphic symbols are used to specify arithmetic operations and relational conditions.
The following are commonly-used arithmetic and relational symbols.
FLOWCHARTING TEMPLATE. - To aid in drawing the flowcharting symbols, you may use a flowcharting template. Figure 3-4 shows a template containing the standard symbol cutouts. A template is usually made of plastic with the symbols cut out to allow tracing the outline.
Figure 3-4. - Flowchart template.
FLOWCHART WORKSHEET. - The flowchart worksheet is a means of standardizing documentation. It provides space for drawing programming flowcharts and contains an area for identification of the job, including application, procedure, date, and page numbers (fig. 3-5). You may find it helpful when you develop flowcharts. If you don't have this form available, a plain piece of paper will do.
Figure 3-5. - Flowchart worksheet.
Constructing a Flowchart
There is no "best way" to construct a flowchart. There is no way to standardize problem solution. Flowcharting and programming techniques are often unique and conform to the individual's own methods or direction of problem solution.
This section will show an example of developing a programming flowchart. It is not the intent to say this is the best way; rather, it is one way to do it.
By following this text example you should grasp the idea of solving problems through flowchart construction. As you gain experience and familiarity with a computer system, these ideas will serve as a foundation.
To develop a flowchart, you must first know what problem you are to solve. It is then your job to study the problem definition and develop a flowchart to show the logic, steps, and sequence of steps the computer is to execute to solve the problem.
As an example, suppose you have taken a short-term second mortgage on a new home, and you want to determine what your real costs will be, the amount of interest, the amount to be applied to principal, and the final payment at the end of the 3-year loan period.
The first step is to be sure you understand the problem completely - What are the inputs and the outputs and what steps are needed to answer the questions? Even when you are specifying a problem of your own, you will find we don't usually think in small, detailed sequential steps. However, that is exactly how a computer operates, one step after another in a specified order. Therefore, it is necessary for you to think the problem solution through step by step. You might clarify the problem as shown by the Problem Definition in figure 3-6.
Figure 3-6. - Problem definition and programming flowchart.
After you have this level of narrative problem definition, you are ready to develop a flowchart showing the logic, steps, and sequence of steps you want the computer to execute to solve the problem. A programming flowchart of this problem is also shown in figure 3-6. Study both the problem definition and the flowchart to see their relationship and content.
You now have a plan of what you want the computer to do. The next step is to code a program that can be translated by a computer into a set of instructions it can execute. This step is called program coding.