Tutorial Series: Free C# Fundamentals via ASP.NET Web Apps
Previous Article | Next Article
In this lesson, you’re going to learn how to return values from methods that you create. Up to this point, you have been working with methods that return void (in other words, nothing at all). The void keyword means that after the method is called, no information is returned back to the calling code block. However, if you replace the void keyword with a type (int, string, DateTime, etc) you must specify within the method the actual value being returned, and the caller will assume that value once the method it has called completes execution.
Some of the helper methods we have been working with thus far have been returning values back to the caller. For example, we know that the int.Parse() method takes in a string, and returns an int. In fact, Intellisense tells us this:
Knowing that int.Parse() returns a value, we can treat it as being that value. Here, we know that the value being returned will be 5, so what can you do with that value? You can do a number of things, and one of them is to assign it to another variable, of type int:
That means that this statement is semantically equivalent to:
And, because those statements are semantically equivalent, you can do this:
Let’s create our own custom method with a return type in a new ASP.NET project called “CS-ASP_030”, which is based on where we left off with the previous lesson. In Default.aspx.cs write in some helper methods that we will later reference in Page_Load():
Tip:
Here again you see the private keyword prefixed to all of these methods. This has to do with whether or not outside classes can access (call) this method/element. This will make sense once you are exposed to Object-Oriented Programming principles in later lessons. However for now know that this keyword means these methods can only be called within the class they’re defined (in this case, the Default class).
These methods should be fairly self-explanatory, however, note that they all just add information to the resultLabel and therefore do not return anything back to the caller. Now, write the following in Page_Load():
Here we are calling the helper methods to display “Battle/Round” header information and then once the battle completes, display the final result. However, this code won’t work properly in its current state, since the while() loop will never break out of just displaying the “Round” header. We will have to write some battle code so let’s do that in another helper method called performAttack() (also, notice the various input parameters we will be using for this method to work):
This method currently consists of applying a random damage value to defenderHealth, and then returning that value to the caller. However, we’re not yet done with this method. We will also want to execute the describeRound() method within the performAttack() method. When you write the call to describeRound(), you will notice that Intellisense will give you a reminder as to the input parameters you are expected to supply:
Tip:
When your variables and input parameters have specific, obvious names, it eliminates confusion over ambiguity when referencing them. In this case, we know that describeRound() needs to take in the attacker's name, defender's name and the defender's health. If these weren't named specifically, their purpose would be unclear.
We will supply these values based on what values are supplied for the outer calling method performAttack(). You can think of it like you are copying these values, whatever they might be, once they are passed in when calling performAttack():
You can now pass in these values by calling the method in Page_Load(), as follows:
Recall that perfomAttack() returns an integer value, so that is why it’s being assigned to monsterHealth int variable. Finally, we’re reusing this attack procedure, so let’s also make a few more calls to it in the main battle logic within the while() loop:
Tip:
There are several methods here that each have a specific purpose (and that’s hinted at by the name we chose for each method). This relates to a general programming concept called the “Single Responsibility” principle. Put simply, the more that you break-up your code into individual modules with a single, direct purpose, the easier it will be to keep track of everything in your code and reduce bugs. Each method that you create should have a single specific purpose to keep from complicating the logic in your project. A good practice is to try to keep your method within 10 lines of code.
Step 5: Run the Application
You can now run the application and see the result of this battle simulation:
Lesson 1 - Series Introduction
Lesson 2 - Installing Visual Studio 2015
Lesson 3 - Building Your First Web App
Lesson 4 - Understanding What You Just Did
Lesson 5 - Working with Projects in Visual Studio
Lesson 6 - Simple Web Page Formatting in Visual Studio
Lesson 7 - Variables and Data Types
Lesson 8 - Data Type Conversion
Lesson 9 - Arithmetic Operators
Challenge 2 - ChallengeSimpleCalculator
Solution - ChallengeSimpleCalculator
Lesson 11 - Conditional If Statements
Lesson 12 - The Conditional Ternary Operator
Challenge 3 - ChallengeConditionalRadioButton
Solution - Challenge Conditional RadioButton
Lesson 13 - Comparison and Logical Operators
Lesson 13 Challenge - First Papa Bob's Website
Solution - Challenge First Papa Bob's Website
Lesson 14 - Working with Dates and Times
Lesson 15 - Working With Spans of Time
Lesson 16 - Working with the Calendar Server Control
Challenge 4 - Challenge Days Between Dates
Solution - Challenge Days Between Dates
Lesson 17 - Page_Load and Page.IsPostBack
Lesson 18 - Setting a Break Point and Debugging
Lesson 19 - Formatting Strings
Challenge 5 - Challenge Epic Spies Assignment
Solution - Challenge Epic Spies Assignment
Lesson 20 - Maintaining State with ViewState
Lesson 21 - Storing Values in Arrays
Lesson 22 - Understanding Multidimensional Arrays
Lesson 23 - Changing the Length of an Array
Challenge 6 - Challenge Epic Spies Asset Tracker
Solution - Challenge Epic Spies Asset Tracker
Lesson 24 - Understanding Variable Scope
Lesson 25 - Code Blocks and Nested If Statements
Lesson 26 - Looping with the For Iteration Statement
Challenge 7 - Challenge For Xmen Battle Count
Solution - Challenge For Xmen Battle Count
Lesson 27 - Looping with the while() & do...while() Iteration Statements
Lesson 28 - Creating and Calling Simple Helper Methods
Lesson 29 - Creating Methods with Input Parameters
Lesson 30 - Returning Values from Methods
Lesson 31 - Creating Overloaded Methods
Lesson 32 - Creating Optional Parameters
Lesson 33 - Creating Names Parameters
Lesson 34 - Creating Methods with Output Parameters
Challenge 8 - Challenge Postal Calculator Helper Methods
Solution - Challenge Postal Calculator Helper Methods
Solution - Mega Challenge Casino
Lesson 35 - Manipulating Strings
Challenge 9 - Phun With Strings
Solution - Challenge Phun With Strings
Lesson 36 - Introduction to Classes and Objects
Challenge - Hero Monster Classes Part 1
Solution - Hero Monster Classes Part 1
Challenge - Hero Monster Classes Part 2
Solution - Challenge Hero Monster Classes Part 2
Lesson 37 - Creating Class Files Creating Cohesive Classes and Code Navigation
Lesson 38 - Understanding Object References and Object Lifetime
Lesson 39 - Understanding the .NET Framework and Compilation
Lesson 40 - Namespaces and Using Directives
Lesson 41 - Creating Class Libraries and Adding References to Assemblies
Lesson 42 - Accessibility Modifiers, Fields and Properties
Lesson 43 - Creating Constructor Methods
Lesson 44 - Naming Conventions for Identifiers
Lesson 45 - Static vs Instance Members
Challenge 10 - Challenge Simple Darts
Solution - Challenge Simple Darts
Lesson 46 - Working with the List Collection
Lesson 47 - Object Initializers
Lesson 48 - Collection Initializers
Lesson 49 - Working with the Dictionary Collection
Lesson 50 - Looping with the foreach Iteration Statement
Lesson 51 - Implicitly-Typed Variables with the var Keyword
Challenge 11 - Challenge Student Courses
Solution - Challenge Student Courses
Lesson 53 - Working with Enumerations
Lesson 54 - Understanding the switch() Statement
Lesson 55 - First Pass at the Separation of Concerns Principle
Lesson 56 - Understanding Exception Handling
Lesson 57 - Understanding Global Exception Handling
Lesson 58 - Understanding Custom Exceptions
Lesson 59 - Creating a Database in Visual Studio
Lesson 60 - Creating an Entity Data Model
Lesson 61 - Displaying the DbSet Result in an ASP.NET GridView
Lesson 62 - Implementing a Button Command in a GridView
Lesson 63 - Using a Tools-Centric Approach to Building a Database Application
Lesson 64 - Using a Maintenance-Driven Approach to Building a Database Application
Lesson 65 - Creating a New Instance of an Entity and Persisting it to the Database
Lesson 66 - Package Management with NuGet
Lesson 67 - NuGet No-Commit Workflow
Lesson 68 - Introduction the Twitter Bootstrap CSS Framework
Lesson 69 - Mapping Enum Types to Entity Properties in the Framework Designer
Lesson 70 - Deploying the App to Microsoft Azure Web Services Web Apps
Papa Bob's Mega Solution Part 1 - Setting up the Solution
Papa Bob's Mega Solution Part 2 - Adding an Order to the Database
Papa Bob's Mega Solution Part 3 - Passing an Order from the Presentation Layer
Papa Bob's Mega Solution Part 4 - Creating the Order Form
Papa Bob's Mega Solution Part 5 - Adding Enums
Papa Bob's Mega Solution Part 6 - Creating an Order with Validation
Papa Bob's Mega Solution Part 7 - Calculating the Order Price
Papa Bob's Mega Solution Part 8 - Displaying the Price to the User
Papa Bob's Mega Solution Part 9 - Creating the Order Management Page