C++

Question 1

Import dictionary

Answer 1

import <unordered_set></unordered_set>

Question 2

Import dynamic array

Answer 2

include <vector></vector>

Question 3

Insert element in a dynamic array

Answer 3

arrayName.push_back(element);

Question 4

Sort dynamic array

Answer 4

include <algorithm></algorithm>

sort(array.begin(), array.end());

Question 5

Loop through elements in an array

Answer 5

for(int element : array)

Question 6

Declare a set

Answer 6

unordered_set<int> newSet;</int>

Question 7

Add element to a set

Answer 7

newSet.insert(element);

Question 8

Check element is in a set

Answer 8

if( newSet.find(potentialElement) != newSet.end() )

Question 9

Array length

Answer 9

array.size()

Question 10

Absolute value

Answer 10

include <cmath></cmath>

abs(value);

Question 11

Get last element in an array

Answer 11

array.back();

Question 12

Using auto types

Answer 12

include <any></any>

auto element;
int intVariable = any_cast<int>(element);</int>

Question 13

Int min/max

Answer 13

include <climits></climits>

INT_MIN
INT_MAX

Question 14

Short min/max

Answer 14

include <climits></climits>

SHRT_MIN
SHRT_MAX

Question 15

Unsigned max

Answer 15

include <climits></climits>

UINT_MAX

Question 16

Long min/max

Answer 16

include <climits></climits>

LONG_MIN
LONG_MAX

Question 17

Array is empty

Answer 17

array.empty();

Question 18

Array swap elements

Answer 18

include <vector></vector>

swap(array[i], array[i+1]);

Question 19

String length

Answer 19

string myString;
myString.length()

Question 20

Create dictionary

Answer 20

include <unordered_map></unordered_map>

unordered_map<char, int> myMap;

Question 21

Max int

Answer 21

max(intOne, intTwo);

Question 22

Min int

Answer 22

min(intOne, intTwo);

Question 23

Set array element

Answer 23

include <vector></vector>

myArray.at(i) = x;
y = myArray.at(i);

Question 24

Get first element in array

Answer 24

include <vector></vector>

myArray.first();
myArray[0];

Question 25

Double ended queue

Answer 25

include <deque></deque>

deque<SomeClass *> myDeque;
myDeque.insert(mySomeClass);
first = myDeque.first();
last = myDeque.back();
size = myDeque.size();

Question 26

Sort array with custom sort function

Answer 26

sort(sortedIntervals.begin(), sortedIntervals.end(),
{ return a[0] < b[0]; });

Question 27

Default generated class methods

Answer 27

• a default constructor X(), that calls the default constructor of each class member and base class,
• a copy constructor X(X const& other), that calls a copy constructor on each member and base class,
• a copy assignment operator X& operator=(X const& other), that calls a copy assignment operator on each class member and base class,
• the destructor ~X(), that calls the destructor of each class member and base class. Note that this default-generated destructor is never virtual (unless it is for a class inheriting from one that has a virtual destructor).
• a move constructor X(X&& other), that calls a move constructor of each class member and base class,
• a move assignment operator X& operator=(X&& other), that calls a move assignment operator on each class member and base class.

Question 28

What cases could warrant the creation of methods where defaults are created?

Answer 28

• when the class uses raw pointers or resources like database connections
• when owned resource life cycles need to be managed

Question 29

When considering default class functions, what is the Rule of 3 and the Rule of 5?

Answer 29

If you need to write the code for one of the x resource management functions, it suggests that your class’s resource handling is not trivial and you certainly need to write the other x – 1. – Rule of x

Rule of 3 is for C++ 98 and Rule of 5 is for C++ 11

Question 30

When does the compiler not generate normally generated default functions?

Answer 30

• when you define them
• if the compiler can’t generate an operator= like when the class contains a const or reference member
• if you write a direct constructor, a copy constructor, or a move constructor
• if you write a copy constructor, copy assignment constructor or delete, then the compiler won’t generate a move constructor
• if you write a move or move assignment constructor, then the compiler won’t generate any other default functions

Question 31

What does = default do?

Answer 31

Forces the compiler to generate the default function.

Question 32

What does = delete do?

Answer 32

Forces the compiler to explicitly remove the default function.

Question 33

What is YAGNI

Answer 33

You Ain’t Gonna Need It

Question 34

What is DRY

Answer 34

Don’t Repeat Yourself

Question 35

static_cast syntax

Answer 35

int i = static_cast<int>(val);</int>

Question 36

static_cast uses

Answer 36

• Compile-time cast that does implicit conversion between types.
• will throw compiler error if conversion is not valid

Question 37

const_cast syntax

Answer 37

Type nonConstValue = const_cast<Type>(constValue);</Type>

Question 38

const_cast uses

Answer 38

• change non-const member in a const function
• to pass const value to a function that does not accept const parameter
• It is undefined behavior to change a value that was initially declared as const
• can be used instead of simple type casting as it will fail if the provided value and the cast value are not the same type
• cast away a volatile flag

Question 39

reinterpret_cast syntax

Answer 39

data_type *var_name = reinterpret_cast <data_type *>(pointer_variable);

Question 40

reinterpret_cast uses

Answer 40

• used to convert a pointer from one type to another
• doesn’t check if the before and after types are the same
• reinterpret_cast is a very special and dangerous type of casting operator. And is suggested to use it using proper data type i.e., (pointer data type should be same as original data type).
• It can typecast any pointer to any other data type.
• It is used when we want to work with bits.
• If we use this type of cast then it becomes a non-portable product. So, it is suggested not to use this concept unless required.
• It is only used to typecast any pointer to its original type.
  Boolean value will be converted into integer value i.e., 0 for false and 1 for true.

Question 41

dynamic_cast syntax

Answer 41

DerivedType* derivedVal = dynamic_cast<DerivedType*>(baseValue);

Question 42

dynamic_cast uses

Answer 42

• cast a base object as a derived type
• runtime check
• requires base to have at least one virtual function
• if cast fails and is casting to a pointer type, it returns NULL
• if cast fails and is casting to a reference type, it throws an error