Lesson 30 - Returning Values from Methods

Tutorial Series: Free C# Fundamentals via ASP.NET Web Apps

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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.

Step 1: Recognizing Method Return Values in Intellisense

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:


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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:


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That means that this statement is semantically equivalent to:


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And, because those statements are semantically equivalent, you can do this:


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Step 2: Create a Custom Method with a Return Type

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():


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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).


Step 3: Calling Methods in the Hero/Monster Page_Load()

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():


cs-asp-030---returning-values-from-methods.008


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):


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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:


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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():


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Step 4: Assigning a Method’s Returned Value to a Variable

You can now pass in these values by calling the method in Page_Load(), as follows:


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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:


cs-asp-030---returning-values-from-methods.013


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:


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Related Articles in this Tutorial:

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

Challenge 1

Solution 1

Lesson 7 - Variables and Data Types

Lesson 8 - Data Type Conversion

Lesson 9 - Arithmetic Operators

Lesson 10 - C# Syntax Basics

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

Mega Challenge Casino

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

Mega Challenge War

Solution - Mega Challenge War

Lesson 52 - Creating GUIDs

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 Challenge

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


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