Can someone please explain exactly what a class is- is it like a function, or a variable, or something??

Hi David..

I admit it is hard for the first time learning Object Oriented programming concept. I also still struggling learning the whole concept of programming. Alright let's start with what a class is?

In the simplest term class can be seen as a template. This is the biggest difference between a functions (or in Java you will hear more it called by the name method) with parameters and classes. Functions job is limited to do computation of the parameters and depends on its specification give outputs from the computation. In the case of classes it serve more as a template. Inside a class there consist of attributes with state inside and functions defining how the class behave. Thus class can be used to define many objects through a process called instantiation.

Take an example of class called car. A car can have different color, different engine capacity, different brand, and so on. The car can be driven if you know the method to drive it. In this example car serve the purpose of defining what car is therefore it is a class. If you buy a car of your own you can choose the color, engine, brand etc. of it and I too can select my own color, engine, brand etc. So you have your own car and I have my own (different car) that means my car and your car are two different object but still defined as a car right? That is simple example of the relation between class and object.

The attribute in your car include color. This color is your own choice and you can modify it if you want and if you can. This is attribute which define the state of the object (your car) and it is part of class (car) definition. Then as for the drive aspect this can be seen as method that define how a car behave. The car can turn left or right depending how you turn the steer. This takes a function to define how the behavior of your car will be. It takes parameters from you like where you turn your steer and how deep you press the acceleration pedal to define the car behavior of direction and speed.

So inside of class (definition) of a car all of this like attribute such as color etc. and method (behavior) how it should be driven is defined. Therefore, every time the factory creates a car to be sold to customers it has to comply with the definition. I guess that is the best I can tell you about. I hope it still useful, and I am sorry if you get even more confused. Any other inputs are welcomed.