Writing a simple class

Now let's create our first class. Let's imagine that we are developing some software for a bank. Our application should keep track of the bank's customers and their bank accounts, and perform some basic actions on those bank accounts. As we are going to design our application using C#, we have to think of our application in an object-oriented way. Some objects that we will need for this application could be a customer object, a bank account object, and other objects. So, to make blueprints of these objects, we have to create a Customer class and a BankAccount class, as well as the other classes that we will need. Let's first create the Customer class using the following code:

class Customer
{
    public string firstName;
    public string lastName;
    public string phoneNumber;
    public string emailAddress;

    public string GetFullName()
    {

        return firstName + " " + lastName;
    }
}

We started with the class keyword and then the name of the class, which is Customer. After that, we added the class body inside curly braces, {}. The variables that the class has are firstName, lastName, phoneNumber, and emailAddress. The class also has a method called GetFullName(), which uses the firstName and the lastName fields to prepare the full name and return it.

Now let's create a BankAccount class using the following code:

class BankAccount {
    public string bankAccountNumber;
    public string bankAccountOwnerName;
    public double amount;
    public datetime openningDate;

    public string Credit(){
        // Amount credited
    }

    public string Debit(){
        // Amount debited
    }
}

Here, we can see that we have followed a similar approach to create a class. We have used the class keyword and then the name of the BankAccount class . After the name, we started the class body with an opening curly brace and entered fields such as bankAccountNumber, bankAccountOwnerName, amount, and openningDate, followed by two methods, Credit and Debit. By placing a closing curly brace, we end the class body.

For now, don't get worried about keywords such as public; we will learn about these keywords later in the book when we talk about access specifiers.