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The System Flowchart:
Although a system flowchart is very helpful and useful in showing the inputs, major processing functions, and outputs of a program, it gives only limited amount of detail about how the computer performs the specific processing steps. The system flowchart doesn’t show all the mathematical operations that are needed or the order in which the operations must be performed. To provide this detailed information, we construct a program flowchart. Sometimes the best way is to work backwards.
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The Sales Application Program: In the System Program and Flowchart Program to the right, a program for computing a weekly sales report is to be written and executed. In this flowchart, for example, we first decide what we need to know to compute a salesperson’s pay. Usually, a salesperson’s pay is determined in part by how much he or she sold in a given week. In this example, the sales will be divided into two categories: those items sold at regular price, and those sold at a reduced or sale price. Each person will be paid a base amount ($200.00) as well as a percentage of his or her weekly sales. This percentage (commission) will be 6 percent on the sales of regular-price items and 3 percent on the sale-priced items. Here is the Sales Application Problem:
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The Temperature Conversion Program: The International Broadcasting Company wants a computer program that will accept a temperature reading expressed in Fahrenheit degrees as input, convert the value to Celsius degrees, and provide both the Fahrenheit value and the Celsius value as output for its hourly weather report. A program flowchart representation of the solution is shown to the right. As you can see Fahrenheit is read as the input. In the next step a mathematical formula is executed to convert this value from Fahrenheit to Celsius. This formula contains three constants (32, 5, and 9) and several mathematical operatorions. The computer will evaluate the mathematical expression in a left-to-right order. Here is the Temperature Conversion Problem:
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The Billing Program: A major department store needs a program to prepare a monthly bill for each customer. For simplicity, let us assume that each customer purchases at most one type of item each month. For purchase, there will be four input value: customer name, item, quantity, and price. The output will be the customer’s monthly bill after a 10 percent discount is taken before taxes, aand then a 5 percent sale tax is added. Here is the Billing Problem:
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