Object Oriented Programming

What’s the difference between structures and classes?

• Struct members are public by default.

• Class members are private by default. 

Are objects instances of classes? True or False?

True

What are the 3 different levels that members can have?

• public-accessible from anywhere

• protected-can only be accessed within the class and by child classes

• private-accessible only inside the class

How does something become a friend of our class?

You use the keyword friend within the class.

What does the .(dot) operator do?

Used to access members of an object directly.

What does the arrow(→) operator do?

Used to access members through a pointer to an object.

Default constructor: When an why is it important to use it?

When it should be used: When you want objects to initialize with default values.

Why should it be used: When you have a constructor with no parameters

Explicit Constructor

When should it be used: When you want to make the conversion intentional.

Why should it be used: When you want to avoid implicit conversions in C++.

What is a destructor?

Special function to clean up when object is destroyed.

When is a destructor called?

Automatically when object goes out of scope or delete is used.

When does a destructor need to be written?

You manually allocate memory or acquire other resources in the class.

Canyou overload a destructor?

No – only one destructor allowed per class.

How do we make a member function constant?

you use the const keyword after the function's parameter list.

Example: int getValue() const

Why would we make a member function
constant?

not to modify the object’s member variables

What is an accessor?

Also known as a getter. It is used to access data.

What is a mutator?

Also known as a setter. It is used to modify private data.

What is a this pointer?

The this pointer refers to the current object on which the member function is being called.

Name 4 features of static members?

• Belongs to a class

• Accessed via ClassName::function

• Does not have a “this” pointer

• Memory is shared

Name 4 features of Non-static members?

• Belongs to individual objects

• Accessed via object.function()

• Has a “this” pointer

• Memory is unique per object

What is composition?

Composition in C++ means that a class is made up of one or more objects of other classes.

When building a uml diagram name what 3 things go in each box(box = classes)?

• Name of the class in the 1st box

• Data members in second box

• Member functions in 3rd box (+public, -private, #protected)