Methods and Classes

Question 1

How do you set a default value for a parameter in a method?

Answer 1

Set the parameter equal to something in the parenthesis.

static void main(string greeting = “Hello”)
{
Console.WriteLine(greeting);
}

Question 2

What are Named Arguments?

Answer 2

Named arguments are a way to create parameters in a method where the order of the params doesn’t matter. You use the key : value syntax for this.

static void MyMethod(string child1, string child2, string child3)
{
Console.WriteLine(“The youngest child is: “ + child3);
}

static void Main(string[] args)
{
MyMethod(child3: “John”, child1: “Liam”, child2: “Liam”);
}

You can also specify which param to call.

static void Main(string[] args)
{
MyMethod(“child3”);
}

Question 3

What is Method Overloading?

Answer 3

Method Overloading is where multiple methods can have the same name with different parameters. This allows the method to behave differently based on the arugments used when it’s called.

Question 4

What is a Constructor?

Answer 4

A special method used to initialize objects. The advantage of a constructor, is that it is called when an object of a class is created. It can be used to set initial values for fields.

Question 5

The constructor name must match the class name, true or false?

Answer 5

True. The constructor also doesn’t have a return type. All classes have a constructor by default. If you don’t create one, the language will create one for you, but you won’t be able to initialize values.

Question 6

What are the four Access Modifiers?

Answer 6

Public, Private, Protected, and Internal.

Question 7

What does the Public Access Modifier do?

Answer 7

Makes the data accessible to all classes.

Question 8

What does the Private Access Modifier do?

Answer 8

Makes the code accessible only inside of the class.

Question 9

What does the Protected Access Modifier do?

Answer 9

Makes the code accessible only inside of the class and any class derived from it.

Question 10

What does the Internal Access Modifier do?

Answer 10

The code is only accessible within its own assembly, but not from another assembly.

Question 11

What are the two combinations of Access Modifiers

Answer 11

Protected internal and private protected

Question 12

What is the default Access Modifier?

Answer 12

Private

Question 13

What keyword do you use if you don’t want other classes to inherit from a class?

Answer 13

Sealed

sealed class Vehicle 
{
  ...
}

class Car : Vehicle 
{
  ...
}

Error message: ‘Car’: cannot derive from sealed type ‘Vehicle’

Question 14

What keyword is used on a base class method to allow it to be overridden?

Answer 14

Virtual

public virtual void animalSound()
{
Console.WriteLine(“The animal makes a sound”);
}

You can also use the abstract keyword.

Question 15

What keyword is used on a derived class method to allow it to be overridden?

Answer 15

Override

public override void animalSound()
{
Console.WriteLine(“The dog says: bow wow”);
}

Question 16

What is an Abstract Class

Answer 16

A restricted class that cannot be used to create objects (to access it, it must be inherited from another class).

abstract class Animal 
{
  public abstract void animalSound();
  public void sleep() 
  {
    Console.WriteLine("Zzz");
  }
}

Question 17

What is an Interface?

Answer 17

A completely “abstract class”, which can only contain abstract methods and properties (with empty bodies).

// interface
interface Animal 
{
  void animalSound(); // interface method (does not have a body)
  void run(); // interface method (does not have a body)
}

Question 18

By default, members of an interface are all abstract and which access modifier?

Answer 18

Public