README.md

Classes and Methods

Objectives

• Declare a class and create an object.
• Declare a method.
• Explain the function of the Main method.

Introduction

There are situations where a program's functionality will ask for solutions that have already been addressed in code. However, rewriting these pieces of code over and over again is not efficient, so C# provides a solution in the form of classes and methods. In C#, a class represents a blueprint or skeleton for an object, which in itself encompasses variables, functions, structure and properties.

Methods are blocks of code that combine different elements (such as variables) to produce a specific result or carry out a specific function. Methods are declared inside of a class, and as such are dependent on it to be re-used.

Declaring a Class and Creating an Object

The following is the syntax to create a class:

class MyClass
{

}

MyClass is the name given to the class, and anything can be chosen for it. The curly braces {} encompass the block of code that pertains to the class.

Inside the block of code, we can create methods and declare variables. We will go deeper into methods in a bit, but these will allow us to add functionality to the program and get or modify information of an instance of the class.

class Dog
{
    public string name;
    public string breed = "Great Dane";
}

Each instance (or object) of the class uses the skeleton or blueprint provided, but is given its own values that identify it as a unique instance. In the Dog class above, we've assigned two attributes. The first is a string for the dog's name and the second is a string for the dog's breed. Essentially, each instance of the Dog class will have a different name. However, the breed for each instance will always be a Great Dane.

Now that the Dog class is created, you can create an object of the class and use the object wherever necessary in your program.

The following is the syntax to create an object.

// We declare objects similar to how we declare variables, using the class name as the 'data type' followed by:
class Dog
{
    public string name;
    public string breed = "Great Dane";
}

Dog myDog = new Dog();
myDog.name = "Baxter";

Console.WriteLine(myDog.name);
Console.WriteLine(myDog.breed);

Declaring Methods

Methods are building blocks, which combine code together to simplify coding. Methods are only run when they are called.

The following is the syntax to create a method:

static void MyMethod ()
{
    // code to be executed
}

In order to declare a method, there is a specific order of elements.

• An access identifier, which determines whether the method can be used by outside code, can be public or private.
• The return type, which depends on the desired outcome of our method. We can return a specific value (by return, programming lingo means resulting in a data value). This will be written as one of the data types we have discussed previously, such as int.
• The method name which can be anything, but should aim to make sense with what the method does to make it clearer for anyone who reads the code.
• The parameters, which are values or variables that are passed into the method for usage.

The following is the syntax to call a method:

MyMethod();

The follow is an example of a method that outputs the string Hello World.

static void HelloWorld()
{
Console.WriteLine("Hello World");
}
HelloWorld();

If you don't need the method to return anything (ex: a method that just writes to the console) you can use the return type void. This returns nothing and requires no return statement.

The following is an example of a method that adds two numbers and returns the resulting value.

//This defines a public access method that returns an int value, and receives the parameters of type int num1 and num2.

public int addTwo(int num1, int num2)
{
    //
    return num1 + num2;
}

The Main Method

The Main method is used across all C# programs. This is where the program begins executing all of a program's objects and methods. A program can contain only one Main method.

The Main method either be a void or int return type and must be declared inside a class. In addition,the Main method requires a static modifier.

The following is the syntax to declare a Main method:

class Program
{
    static void Main(string[] args)
    {
        //Here goes the content of the program
    }
}

Post-Lecture Quiz

Quiz

Review and Self Study

We've identified the following resources to provide additional context and learning for the content reviewed in this lesson. We encourage you to review the material below and explore additional related topics.

• C# Methods
• C# Object and Collection Initializers