Well, it looks as if you are attempting to write the constructor for your class. You are passing in some values, and you probably want to save them so that you can work on them later. So my guess is that the function should be written as:
sets the value of the parameter to its own value. You want to set the "size" class variable to the "size" parameter value. Since the code is somewhat ambiguous, the compiler defaults to working on the parameters.
To make the code unambiguous, and to make it work correctly, you need to tell the compiler you are attempting to set the class variable, not the function parameter. You can do this via