10.6. Chapter Review

Follow the lab assignment format to prepare this assignment.
Create a project folder called Ch10Classes to include the code for this project.
Question 6~10 require code and execution screenshots when applicable.

What is the keyword used to create an instance of a class?
Can you create an object from a class resides in another file?
What is the purpose of a constructor?
Describe the process of implementing inheritance in polymorphism in steps.
If you want to use an instance variable (field) in a method, should you declare that instance variable in the method? Why?

How do you create an instance of the following class?

class DoMath
{
    public int Sum(int num1, int num2)
    {
        var total = num1 + num2;
        return total;
    }
}

How do you use the following class to use the Sum method for summing up two integers? Prepare your code in your Program.cs Main method.

static class SomeMath
{
    public static int Sum(int a, int b)
    {
        return a + b;
    }
}

Define a Math class, when instantiated, offer the functionality of two summing methods with the same name Sum that would take 2 and 3 arguments, respectively, and sum them up and return the results.
Change the preceding code to allow the passing of an unspecified number of integer arguments (see, e.g., https://stackoverflow.com/questions/1996426/pass-multiple-optional-parameters-to-a-c-sharp-function). Save the file in the project folder,call it SumManyArgs.cs and use SumManyArgs as the class name.
Does the following code define a public or private class? Add an access modifier without changing the existing accessibility level. Show your changed code and explain why.
```
class Customer
{
    // Fields, properties, methods and events go here...
}
```