C++

Question 1

What are the 5 properties of OOP languages such as C++? Define each…

Answer 1

Abstraction -> Group associated features into on place for use.
Polymorphism -> Objects of the same type can take different forms.
Encapsulation -> All implementations are encapsulated for security, accessibility,
Inheritance -> Allows for diverse implementations of a single interface and documentation.
Extensibility -> Enables classes to extend functionality of other classes.

Question 2

What header is needed for basic IO commands? What are the commands used for character input and output?

Answer 2

include <iostream></iostream>

std::cout -> Writes character stream to console.
std::cin -> Reads character stream from keyboard.

Question 3

What do constructors and destructors return?

Answer 3

Nothing.

Question 4

Explain when and how to use the ‘this’ keyword…

Answer 4

this is a pointer to the immediate scope of the class. For example, if used in a constructor, it will point to the variable outside of the constructor scope.

Question 5

How do we differentiate the public, protected and private members of a class?

Answer 5

Public:
Protected:
Private:

Question 6

In regards to dynamic memory allocation to pointers in the class, what happens upon instantiation of an object?

Answer 6

The required memory is automatically allocated to the pointers.

Question 7

In regards to memory allocation, what happens when the destructor is called?

Answer 7

Allocated memory is freed.

Question 8

How do we declare the destructor?

Answer 8

~MyClass();

Question 9

When is the destructor called?

Answer 9

When delete(Object) is called on the object.

Question 10

What is the purpose of a Copy Constructor?

Answer 10

It’s a way to assign members of an object instances based on another instance of the same object.

Question 11

How do we declare a Copy Constructor?

Answer 11

MyClass ( const MyClass & )

Question 12

How can we access functions outside the scope of their declaration? Use a class name Person and function named getAge() as an example…

Answer 12

Person::getAge();

Question 13

Is function overloading possible?
How do we set a default argument?

Answer 13

Yes.
setAge( int x = 28 ) { }

Question 14

Which keyword dynamically assigns memory to a pointer type? Which keyword frees this memory?

Answer 14

new
delete

Question 15

What’s the difference between new and malloc?

Answer 15

New allocates memory and calls the constructor, whereas malloc only allocates memory.
New also calculates the memory for you, rather than having to explicitly declare it.

Question 16

What’s the difference between delete and free?

Answer 16

Delete de-allocates memory and calls the destructor, whereas free only de-allocated memory.

Question 17

How do we return a reference from a function?

Answer 17

char &setValue() -> returns a reference to a character.

Question 18

How do we declare a class that extends another class?

Answer 18

class Derived: public Base { };

Question 19

What are the 3 access specifiers? And what access do derived classes have to base variables declared with each?

Answer 19

Public -> Derived classes can access directly.
Protected -> Derived classes can only access via a public function that returns the Protected variable. However, function can be located in the derived class.
Private -> Derived classes can only access via a public function from the base class, in the same class as the private variable.

Question 20

Is it possible to conduct multiple inheritance?

Answer 20

Yes. Through chaining the : operator.

Question 21

Which access specifier should you try to use?

Answer 21

Public where possible.

Question 22

What does using the Private specifier protect the base class from?

Answer 22

Being affected by changes to the derived class.

Question 23

When the main function is returned, what happens regarding the destructors of instantiated objects ?

Answer 23

The return statement calls all the destructor of all objects in the main function.