C++ Basics

Question 1

What is the auto keyword? Provide an example.

Answer 1

Auto can be used during assignment to automatically set a variable to the type of it’s assigned variable.

Question 2

What are the three ways to assign a value to a variable (e.g. int)?

Answer 2

a = 5;
b(3);
c{2};

Question 3

Can you create a new type?

Answer 3

Yes, with the typedef keyword

Question 4

What is the alternative way of writing false?

Answer 4

0

Question 5

What is the alternative way of writing true?

Answer 5

1 (or ‘non-zero’)

Question 6

What is the structure of a C++ array?

Answer 6

type name [size]

Question 7

What is a null character in a string?

Answer 7

‘\0’

Question 8

How do you get the memory address of that variable? E.g. int x = 7;

Answer 8

&x

Question 9

Why do we need pointers?

Answer 9

-dynamically allocate memory

–you can write programs that can handle unlimited amounts of memory-allow a function to modify a variable passed to it

-easier to pass around the location of a huge amount of data than passing the data itself

Question 10

How do you define a pointer?

Answer 10

*p;

int *y;

Question 11

How can we get the content of the memory address pointed to by the pointer?

Answer 11

By using the dereference operator ‘*’

int x = 10;
//variable x = 10

int* y = &x; 
//pointer variable y = Address of x

int z = *y;
//z = “value pointed to by y” = x, i.e. z = x;

Question 12

What is the l-value?

Answer 12

The expression that refer to a memory location e.g. a variable

Can be both side

Question 13

What is the r-value?

Answer 13

The data stored in some memory address (can only be on the right side)

Question 14

What are the compound data types in C++?

Answer 14

Any type that isn’t a primitive.

Arrays
Char sequences
Strings
Pointers
Dynamic memory
Data structures

Question 15

Can pointers be declared as constants?

Answer 15

Yes but can’t change memory address

Question 16

When casting to a lower size type - what happens to the value?

Answer 16

You chop the size of the lower type on the higher type from the LSB up to the size of the type

0000 0001 0100 0000 (short 2 bytes)
                    0100 0000 (char 1 byte)

Question 17

What is the difference between a class and structs?

Answer 17

Struct members are public by default

Question 18

Why use an enum?

Answer 18

Restricted set of variables

Question 19

How do access the attribute ‘name’ from a ‘Person’ struct Declared ‘Person person’?

Answer 19

person.name;

Question 20

How do access the attribute ‘name’ from a ‘Person’ struct Declared ‘Person * person = new Person’?

Answer 20

person->name;

Question 21

Is it possible to have arrays of structs?

Answer 21

Yes

Question 22

Where would you use an array of structs?

Answer 22

A database

Question 23

In OOP what are three things to consider with structs?

Answer 23

Member accessibly
Code visibility
Encapsulation

Question 24

What are the five program memory components?

Answer 24

Code segment
BSS Segment
Data Segment (DS)
Heap
Stack

Question 25

What is contained in the BSS segment?

Answer 25

all uninitialized, global and static

Question 26

What is contained in the DS segment?

Answer 26

Initialized variables

Question 27

What are the three types of memory allocation in C++?

Answer 27

Static
Automatic
Dynamic

Question 28

What is static memory used for?

Answer 28

For static and global variables

Question 29

What is automatic memory used for?

Answer 29

For local variables and function params

Question 30

What is static memory used for?

Answer 30

Heap memory

Question 31

For function overloading, what part of the signature isn’t considered for uniqueness?

Answer 31

the return type

Question 32

What are the types available for integral promotion to int?

Answer 32

bool, char and short

Question 33

What value is used for the return type in a template function?

Answer 33

The left most type

Question 34

What issue may arise from template functions with different types?

Answer 34

Might end up with a type you weren’t expecting

Question 35

When do you use virtual?

Answer 35

To declare an overridable method in a parent class