Refresher on Functions and Classes 1

Question 1

What is an Iterator in C++?

Answer 1

An object that can traverse a container class without the user knowing how the container is implemented.

Examples include std::map and std::vector.

Question 2

What types of iterators do containers provide?

Answer 2

• iterator: read/write iterator
• const_iterator: read-only iterator

Question 3

What does the begin() function return?

Answer 3

An iterator representing the beginning of the elements in the container.

Question 4

What does the end() function return?

Answer 4

An iterator representing the element just past the end of the elements.

Question 5

What is the purpose of the dereference operator (*) for iterators?

Answer 5

To return the element that the iterator is pointing at.

Question 6

What does the operator++ do for iterators?

Answer 6

Moves the iterator to the next element in the container.

Question 7

What is a set in C++?

Answer 7

A collection of unique values containing no duplicates, stored in sorted order.

Question 8

What happens when you try to insert a duplicate value into a set?

Answer 8

The duplicate value does not get added.

Question 9

What does the find() method do in a set?

Answer 9

Returns an iterator pointing to the element if it exists or end() if it does not.

Question 10

What is a map in C++?

Answer 10

An associated container that has a key/value mapping with unique keys.

Question 11

What is the difference between a set and a map?

Answer 11

A map has a value associated with each unique key, while a set only contains unique values.

Question 12

What does the insert() method expect when adding to a map?

Answer 12

An std::pair representing the key and value.

Question 13

What is a function template in C++?

Answer 13

A template that allows the creation of functions that can operate on different data types.

Question 14

What is the syntax to declare a template for a single type?

Answer 14

template <typename></typename>

Question 15

What is the purpose of the Rule of 3 in C++?

Answer 15

It states that if a class manages resources, it should define a destructor, copy constructor, and copy assignment operator.

Question 16

What does the term ‘deep copy’ mean?

Answer 16

Creating a new copy of an object along with all objects it references.

Question 17

What is meant by ‘shallow copy’?

Answer 17

Copying an object while sharing references to the same resources it points to.

Question 18

What is the purpose of a constructor in a C++ class?

Answer 18

To initialize an object when it is created.

Question 19

What does the term ‘accessor’ refer to in C++ classes?

Answer 19

A member function that retrieves the value of a private member variable.

Question 20

Fill in the blank: A _______ is an object that can traverse a container class.

Answer 20

Iterator

Question 21

True or False: A set can contain duplicate values.

Answer 21

False

Question 22

What is the output of the following piece of code? std::vector<int> nums = {10, 20, 30, 40, 50}; std::vector<int>::iterator it = nums.begin(); while (it != nums.end()) { if (*it % 20 == 0) { it = nums.erase(it); } else { ++it; } } for (it = nums.begin(); it != nums.end(); ++it) { std::cout << *it << ' '; }</int></int>

Answer 22

10 30 50

Question 23

What does the erase() function do in a vector?

Answer 23

Removes an element from the vector and returns an iterator to the next element.

Question 24

What data structure is assumed to be used in the set class?

Answer 24

Binary Search Tree

This could have been any data structure.

Question 25

What is the purpose of a constructor in a class?

Answer 25

Helps with initialization ## Footnote Same name as the class, no return type.

Question 26

What is a default constructor?

Answer 26

No arguments passed

Question 27

What is a parameterized constructor?

Answer 27

Constructor with arguments

Question 28

What is a copy constructor?

Answer 28

Takes an existing object and sets all of its fields to the fields of that object

Question 29

What does the destructor do in a class?

Answer 29

Destroys objects created by a constructor

Question 30

When is a destructor called?

Answer 30

When a reference to an object goes out of scope or when a pointer to the object is called with delete

Question 31

What is the copy assignment operator used for?

Answer 31

Overloads the assignment operator =

Question 32

What is the difference between a copy constructor and an assignment operator?

Answer 32

Copy constructor creates a new object, assignment operator copies data into an existing object

Question 33

What is data hiding/abstraction?

Answer 33

Use private/public access to members

Question 34

What are accessor functions?

Answer 34

Functions that return private members’ values

Question 35

What are mutator functions?

Answer 35

Functions that set private members’ values

Question 36

What is the difference between deep copy and shallow copy?

Answer 36

Deep copy copies contents to a different memory location, shallow copy copies the reference of memory

Question 37

What is the Rule of Three in C++?

Answer 37

If you implement copy constructor, destructor, or assignment operator, you should implement all three

Question 38

What does the Rule of Five add to the Rule of Three?

Answer 38

It adds rules for move semantics

Question 39

What is the purpose of a class constructor?

Answer 39

To initialize an object of the class

Question 40

What does the statement 'set s4 = s2;' invoke?

Answer 40

The copy constructor of the s4 object

Question 41

What is a template in C++?

Answer 41

A feature that allows functions and classes to operate with generic types

Question 42

Fill in the blank: A function that simply ______ private members’ values is called an accessor function.

Answer 42

returns

Question 43

True or False: A destructor has parameters.

Answer 43

False

Question 44

What does the copy assignment operator require before copying new data?

Answer 44

Deleting any existing data

Question 45

What type of access do private members have?

Answer 45

Cannot be directly accessed using an object

Question 46

What is the primary reason to implement a deep copy in a copy constructor?

Answer 46

To avoid shared references to the same memory

Question 47

What is the purpose of the 'this' pointer in a member function?

Answer 47

To refer to the current object

Question 48

Fill in the blank: The ______ constructor is called when creating a new object from an existing one.

Answer 48

copy

Question 49

What is the main objective of using function templates?

Answer 49

To enable functions to operate with generic types

Question 50

What is the purpose of the getter function getVector() in the MyVec class?

Answer 50

To return the vector v ## Footnote The getter function allows access to the private member v of the class.

Question 51

What is the first step in the copy constructor MyVec::MyVec(MyVec &myvec) for deep copying?

Answer 51

Create a new vector() ## Footnote This initializes a new vector to store copied elements.

Question 52

In the deep copy constructor, what does the loop do?

Answer 52

Copies elements from myvec's vector to the new vector ## Footnote The loop iterates through each element of myvec's vector and pushes it into the new vector.

Question 53

Which of the following options indicates a deep copy in the MyVec class?

Answer 53

Code A ## Footnote Code A creates a new vector and copies each element, ensuring that the original vector and the copied vector do not reference the same memory.

Question 54

What is the issue with the second version of the copy constructor MyVec::MyVec(MyVec &myvec)?

Answer 54

It does not perform a deep copy ## Footnote This version assigns the entire myvec to v, which can lead to shared references.

Question 55

What mistake is present in the third version of the copy constructor MyVec::MyVec(MyVec &myvec)?

Answer 55

It assigns myvec's vector directly to v ## Footnote This creates a shallow copy, where v and myvec's vector point to the same memory location.

Question 56

What does the term 'deep copy' mean in the context of the MyVec class?

Answer 56

Creating a new instance of the vector with its own memory ## Footnote A deep copy ensures that changes to one vector do not affect the other.

Question 57

Fill in the blank: The variable v in the MyVec class is of type _______.

Answer 57

vector ## Footnote This defines v as a vector that holds integers.

Question 58

True or False: A shallow copy in MyVec would mean both instances share the same vector memory.

Answer 58

True ## Footnote If a shallow copy is made, modifications to one instance would affect the other.