Now for the main event. Let's turn the checkerboard code into a board class. I'll create a new console app called checkerboard and open it by dragging the folder onto visual Studio Code.

A class is a definition of an object, and an object is both a variable and functionality, although, in the context of classes, functions are called methods. It will come as no surprise that a class is defined with the keyword class followed by the class's name. Everything inside the curly braces is the class definition. Within the class, we define variables to hold an object's data. A class can be likened to a compound variable made up of other variables as a molecule is made up of atoms. Having said that, variables inside a class don't have to be simple data types like numbers or text. A class definition can contain other classes as variables. Strictly speaking, variables defined in a class are called members. Member variables are also defined by their visibility.  Checkers, rows, and columns are private, which means they are only visible and used within the class. Members can also be defined as public or protected, which we'll see later. Every class has a constructor function that runs when a new instance of the class is created. The constructor has public visibility, so code external to the class can make an instance of the class, and the constructor has the same name as the class. A class can have multiple constructor functions, all with the same name, as long as they have different parameter signatures. A function's signature is the number and data types of the parameters. I could have additional Board constructors with no parameters, one with an int and a string parameter, or one with three int parameters. I can't have another constructor with two int parameters, even if the parameters have different names. Because a board has to have at least some rows and columns, I've got one constructor that takes two int parameters. These parameters are only visible to the constructor function, so I'll assign them to the rows and columns members to make them visible to the whole class.

As with the previous code, I still need to create an instance of the checkers array within the board class. However, this time I'll use rows and columns to define the array boundaries, making the board size dynamic. Next, I'll create a private function Setup to populate the checkers array, using similar logic as already seen, and call Setup from the constructor. Finally, we need a print function, so I'll copy Setup with its nested for loops and enter the Console.Write statements. To use the class or put more correctly instantiate an instance of the class, declare a Board variable, and use the new operator with the class constructor. The C# language extension recognizes our class as a new data type, color coding appropriately, and the IntelliSense tooltips also recognize the board as a class. Except I can't see the print function. Why is that? Well, like private variables, private functions are only visible within the class, so I need to change print from private to public. There we go; the print method is now visible. Let's save and run. It looks like we've got a winner, refactoring the checkerboard code into a class that produces the same checkerboard pattern. We're not done yet. Next, we'll refine our code, introducing more flexibility and validation.