Creating Methods that Return a Value

For example, a method that returns the number of hours an employee has worked might have the following header:
num getHoursWorked()
This method returns a numeric value, so its type is num .
When a method returns a value, you usually want to use the returned value in the calling method, although this is not required.
For example, Figure 9-8 shows how a program might use the value returned by the getHoursWorked() method. A variable named hours is declared
in the main program. The getHoursWorked() method call is part of an assignment statement.
When the method is called, the logical control is transferred to the getHoursWorked() method, which contains a variable named workHours . A value is obtained for this variable, which is returned to the main program where it is assigned to hours . After logical control returns to the main program from the getHoursWorked() method, the method’s local variable workHours no longer exists. However, its value has been stored in the main program where, as hours , it can be displayed and used in a calculation.

Figure 9-8, notice the return type num that precedes the method name in the getHoursWorked() method header. A method’s declared return type must match the type of the value used in the return statement; if it does not, the program will not compile.
A numeric value is correctly included in the return statement—the last statement in the getHoursWorked() method. When you place a value in a return statement, the value is sent from the called method back to the calling method.
A method’s return statement can return one value at most. The returned value can be a variable or a constant. The value can be a simple data type or a complex data type.
For example, in Chapter 10 you will learn to create objects, which are more complex data types.
You are not required to assign a method’s return value to a variable to use the value. Instead, you can use a method’s returned value directly, without storing it. You use a method’s value in the same way you would use any variable of the same type. For example, you can output a return value in a statement such as the following: output "Hours worked is ", getHoursWorked()
Because getHoursWorked() returns a numeric value, you can use the method callgetHoursWorked() in the same way that you would use any simple numeric value.
Figure 9-9 shows an example of a program that uses a method’s return value directly without storing it.
The value of the shaded workHours variable returned from the method is used directly in thecalculation of gross in the main program.





Figure 9-10.The method accepts three parameters and returns the largest of the values. Although this method works correctly and you might see this technique used, its style is awkward and not structured. . The return statements in Figure 9-10 violate this
convention by leaving decision structures before they are complete.
Figure 9-11 shows the superior and recommended way to handle the problem. In Figure 9-11, the largest value isstored in a variable. Then, when the nested decision structure is complete, the stored value is returned in the last method statement




Using an IPO Chart
When designing methods to use within larger programs, some programmers find it helpful to use an IPO chart , a tool that identifies and categorizes each item needed within the method aspertaining to input, processing, or output. For example, consider a method that finds the smallest of three numeric values. When you think about designing this method, you can start by placing each of its components in one of the three processing categories, as shown in Figure 9-12.



The IPO chart in Figure 9-12 provides an overview of the processing steps involved in the method. Like a flowchart or pseudocode, an IPO chart is just another tool to help you plan the logic of your programs. Many programmers create an IPO chart only for specific methods in their programs and as an alternative to flowcharting or writing pseudocode. IPO charts provide an overview of input to the method, the processing steps that must occur, and the resulting output.

TWO TRUTHS & A LIE
Creating Methods that Return a Value
1. The return type for a method can be any type, which includes numeric, character, and string, as well as other more specific types that exist in the programming language you are using.
2. A method’s return type must be the same type as one of the method’s parameters.
3. You are not required to use a method’s returned value.

WHICH OF THEM IS A LIE?