Problem 20 - C# Programming: From Problem Analysis to Program Design

Question

Given the following task,which would be the most appropriate method heading? Results have been calculated for taxAmount and totalSales.Write a method heading that accepts these values as input for display purposes. a. public static DisplayResults( ) b. public DisplayResults(double) c. public static void DisplayResults( ) d. public static void DisplayResults(double taxAmount, double totalSales) e. public static void DisplayResults(taxAmount, totalSales)

Step-by-Step Solution

Answer

The correct method heading is option d.

Step 1: Understand the Purpose of the Method

The task is to write a method heading that will accept the values for 'taxAmount' and 'totalSales' to be used for display purposes. This implies the method will likely be used to show the values on a screen or interface.

Step 2: Define the Return Type

Since the task specifies display purposes and does not mention returning a value, the method should have a return type of 'void'. This indicates that the method performs an action but does not return a value.

Step 3: Determine the Method Modifiers

The method heading should include 'public' and 'static'. 'Public' means that the method can be accessed from outside the class, and 'static' means that it can be called on the class itself without creating an instance.

Step 4: Select the Correct Parameter List

Since the method needs to accept 'taxAmount' and 'totalSales' as inputs, the parameter list should include both of these as 'double' data types: 'double taxAmount, double totalSales'. This matches the values that have been calculated.

Step 5: Choose the Best Answer

The most appropriate method heading, considering the need for parameters and the required 'public static void' specifier, is option D: 'public static void DisplayResults(double taxAmount, double totalSales)'.

Key Concepts

Method Declaration

When writing a method in C#, it's essential to understand how to declare it properly, set the right purpose, and structure it to perform a specific task. A method declaration in C# includes several components:

• The access modifier (like public), dictating the visibility of the method.
• The return type, which specifies what type of value the method returns.
• The method name, which should clearly describe what the method does.
• The parameter list enclosed in parentheses. This list specifies the data that the method needs to perform its task.

Method declarations are placed inside a class, and they provide a blueprint for what the method is supposed to do. It is crucial to ensure that each part of the declaration aligns with the method's intended use. For example, in the original exercise, the method's purpose was to handle two input variables for display purposes, which must be clearly reflected in the method heading.

Void Return Type

The void return type in C# indicates that a method does not return a value. This is useful when the method's primary role is to perform an action rather than calculate and return data. Methods with a void return type are commonly used for tasks like displaying information, updating user interfaces, or modifying data without needing to give anything back in return.

When you use void in a method declaration, it signifies that the end goal of the method isn't to provide data but to complete an action. Take the exercise's need for a display function—since its role is to showcase certain pieces of data rather than compute them, it has a void return type. This aligns with the choice of option D in the original exercise, emphasizing void since the method's job is centered around display, not outputting values.

Static Methods

In C#, static methods belong to the class itself rather than any particular instance of the class. This makes it possible to call them even if no object of the class has been instantiated. Static methods are useful when you want to perform a function that doesn't rely on any instance-specific data.

• They are called using the class name, not an object instance.
• They can only access static data or other static methods within the same class.
• They are commonly used for utility or helper functions.
  

For instance, since the DisplayResults method in our exercise is used to showcase calculated values, making it static makes sense, providing easy access anywhere within the program without needing to create an instance of any class.

Method Parameters

Method parameters in C# are crucial for passing data into a method, allowing it to perform tasks based on specific inputs. They act as placeholders for the values that will be passed to the method when it's called.

• Parameters are defined in the method's parentheses, specifying the type and name for each piece of data needed.
• They can have default values, making some optional if not explicitly provided.
• Parameters enable flexibility, allowing the same method to perform slightly different tasks based on the input values.
  

In the exercise, the DisplayResults method has parameters named taxAmount and totalSales, both doubles. This implies that whenever DisplayResults is called, it requires these two pieces of data to execute properly. Selecting and declaring the correct parameters ensures that the method receives all necessary data to perform its role effectively.