Estudo de C++

Question 1

Dereference operator

Answer 1

Give access to real valor on the variable

Question 2

Reference operator

Answer 2

Give access to memory address

Question 3

Keyword New

Answer 3

Creates and initializes objects with dynamic storage

Question 4

Keyword Delete

Answer 4

Erase variables after use

Question 5

Struct

Answer 5

structure for grouping variables, from different types

Question 6

Classes

Answer 6

Extension of struct concept, can have functions

Question 7

Data in structs

Answer 7

Atributes

Question 8

Functions in Classes

Answer 8

Also called methods

Question 9

Object

Answer 9

Takes attributes and methods from classes

Question 10

Object

Answer 10

We use it to access what is in classes

Question 11

Default classes

Answer 11

Everything after a declared class and before a specifier is PRIVATE

Question 12

Scope operator

Answer 12

::

Question 13

Scope operator definition

Answer 13

To show that a function is a implementation from a member from a class, not a global function

Question 14

Constructor

Answer 14

Special method called when a new object is created

Question 15

Using Constructor

Answer 15

Need to have the same name as the classes and no return valor, even VOID

Question 16

Destructor

Answer 16

Called when an object is destroyed(when a function ends or when we use DELETE

Question 17

Using Destructor

Answer 17

Need the same name as the class and a precede “~”

Question 18

Destructor advantages

Answer 18

Good for memory releasing

Question 19

Common practices in C++ with classes

Answer 19

Creating two separated files

Question 20

pragma once

Answer 20

Preprocessor directive to include the header once, regardless how many times he has been imported

Question 21

Declaring a classes as STATIC

Answer 21

We don’t need to instantiate a classes for using it

Question 22

Static class example

Answer 22

“static int math::pow();”

Question 23

Non static class example

Answer 23

"Math math = new Math();"
"math.pow();"

Question 24

Function in static class

Answer 24

Need to be static too

Question 25

Constructor types

Answer 25

Most time are publics, but i can have private constructor too

Question 26

How many constructs can I have?

Answer 26

Classes can have multiples constructors

Question 27

What happens if I don’t create a constructor?

Answer 27

My compiler creates a constructor automatically

Question 28

How many default constructors a class have?

Answer 28

One, and just one

Question 29

Default constructor example

Answer 29

class Person
{
    public:
        Person();
        ~Person();
};

Question 30

From what should I make sure to initialize my own constructor?

Answer 30

Because pointers and arrays can initialize with undefined values.

Question 31

The complex reason for my own constructor?

Answer 31

When I have a class inside a class, my compiler is unable to initialize that member

Question 32

Summarizing the ‘this’ operator - pt 1

Answer 32

This serves for refer to attributes and methods from a class

Question 33

Summarizing the ‘this’ operator - pt 2

Answer 33

When you create an object(instantiate a class), you pass the values in the constructor and we can have methods overloading.

Question 34

Summarizing the ‘this’ operator - pt 3(when use it)

Answer 34

Use the ‘this’ operator when I need to access anything inside a class

Question 35

Keyword ‘new’

Answer 35

It’s used for allocate memory for an object in execution time

Question 36

Keyword ‘delete’

Answer 36

Releases memory after using an object and it’s no more needed

Question 37

Class Scope

Answer 37

In classes context, refer to member variables and member functions within the class definition

Question 38

Inside a class

Answer 38

Every variable and function is available for the functions inside the class

Question 39

Members modifiers

Answer 39

Every member from a class can have access to modifiers like ‘private’, ‘public’ and ‘protected’

Question 40

Private and public members availability

Answer 40

All the members are available for all members functions inside the class

Question 41

Accessing members inside a class

Answer 41

When accessing I need to use the dot operator(‘.’) or arrow(‘->’)

Question 42

Difference between dot and arrow

Answer 42

They have no difference, since they perform the same, but arrows it’s normally used with pointers and dot with variables

Question 43

Why use the arrow ->?

Answer 43

To replaces the following syntax:

(*a).b

Question 44

Accessing statics classes

Answer 44

I need to use the class name like “Math::Sum() instead instantiating like “Math myMath” and after this “myMath.Sum()”

Question 45

The compiler and class scope concept

Answer 45

The compiler knows what function he needs to call, because the object used it’s associated with an specific class. He knows the difference between ‘person.SayHello()’ and ‘dog.SayHello()’

Question 46

Encapsulation concept in OOP

Answer 46

We can say that it allows to include data and functionalities in a single package.

Question 47

The second definition of encapsulation

Answer 47

It’s to hide or restrict data. For example we don’t want to a Person class User defines the variables “firstName”, ‘lastName’ and age directly, only using the constructor

Question 48

A good practice within encapsulation scope

Answer 48

A good practice is to provide public functions to allow classes users to modify values, but indirectly

Question 49

Using a public function to modify allow me to do…

Answer 49

M, as a programmer, control how the users data are processed

Question 50

An example of treated data…

Answer 50

I can use a function to check if a user passed a negative value or a character instead a valid value for an age variable

Question 51

Resuming encapsulation

Answer 51

When using it, we define how attributes and methods are accessed

Question 52

Limiters…

Answer 52

private, public and protected

Question 53

The important part of encapsulation?

Answer 53

That the user don’t see how we define values or validates data

Question 54

The encapsulation analogy

Answer 54

We don’t need to know how a motor inside a car works, I need only to know how to drive him

Question 55

Namespaces

Answer 55

He acts like a container, we put variables, classes or another identifiers to avoid name conflicts

Question 56

Namespaces example: cout

Answer 56

He exists only in the std scope, that’s why we use:
std::cout or
using namespace std;
cout &laquo_space;‘Hello world’ &laquo_space;endl;