Standard Libraries

Question 1

How do you include the string library?

Answer 1

include

Question 2

How do you convert from a string to integer?

Answer 2

std::stoi(my_string);

Question 3

How do you convert from a string to a double?

Answer 3

std::stod(my_string);

Question 4

How do you convert from double/integer to string?

Answer 4

std::to_string(my_new_int);

Question 5

What is concatenating strings? How is it done?

Answer 5

This is combining strings.

std::string combined = string_1 + string_2 + string_3;

Question 6

How do you obtain the first character from a string?

Answer 6

forename.front();

Question 7

How do you obtain a specific character from a string?

Answer 7

forname[3];

Question 8

How do you insert a string into another string?

Answer 8

combined.insert(6, sub_string);

Question 9

how do you obtain a string from within another string?

Answer 9

combined.substr(0,3);

where 0 is the first letter and 3 is the 4th letter

Question 10

How do you include the complex library?

Answer 10

include

Question 11

How do you declare a complex variable?

Answer 11

std::complex c(2.0, -1.0);

Question 12

How do you extract the real part of a complex variable?

Answer 12

c.real()

Question 13

How do you extract the imaginary part of a complex variable?

Answer 13

c.imag()

Question 14

How do you calculate the magnitude of the complex variable?

Answer 14

std::abs(c);

Question 15

How do you calculate the phase angle of the complex variable?

Answer 15

std::arg(c);

Question 16

How do you include vectors?

Answer 16

include

Question 17

How do you declare a vector?

Answer 17

std::vector v;

Question 18

How do you calculate the number of elements of the vector?

Answer 18

v.size();

Question 19

How do you select an element in a vector?

Answer 19

v[2];

Question 20

How do you add elements to a vector?

Answer 20

v.push_back(2);

Question 21

How do you remove the last element from a vector?

Answer 21

v.pop_back();

Question 22

How do you get the first element of a vector?

Answer 22

v.begin();

Question 23

How do you get the last element of a vector?

Answer 23

v.end();

Question 24

How do you insert an element into a vector?

Answer 24

v. insert(v.begin(),6);

v. insert(v.begin() + 3,6);

Question 25

How do you remove elements from a vector?

Answer 25

v.erase(v.begin(), v.begin() + 3);

Question 26

How do you sort elements in a vector in ascending order?

Answer 26

std::sort(v.begin(), v.end());

Question 27

How do you iterate through the elements of a vector?

Answer 27

for(std::vector::iterator i = v.begin(); i < v.end(); i++) {
std::cout&laquo_space;*i &laquo_space;std::endl;
}

Question 28

How do you sort elements in a vector in a descending order?

Answer 28

std::sort(v.begin(), v.end(), sort_descending);

Question 29

What is a map?

Answer 29

This an array where each element is not tied to a specific number but instead tied to a string.

Question 30

What is the string tied to an array position is referred to as:

Answer 30

Key

Question 31

how do you include map?

Answer 31

define

Question 32

How do you create a map?

Answer 32

std::map int_map;

Question 33

How do you add elements to a map?

Answer 33

int_map[“Name”] = 39;

Question 34

How do you erase elements from a map?

Answer 34

int_map.erase(“Evans”);

Question 35

How do we select elements from a map?

Answer 35

To get the key we use: ->first

To get the value we use: ->second

Question 36

How do you iterate through maps?

Answer 36

for(i = int_map.begin(); i != int_map.end(); i++) {
std::string key = i-> first;
int value = i->second;
}

Question 37

How do you obtain te values of a map without knowing its position?

Answer 37

int value = int_map[“Name”];

Question 38

How do you check to see if a key exists? What does it return?

Answer 38

int_map.count(key);

> Returns an integer number of times that that key is found

Question 39

How do you include bitset?

Answer 39

include

Question 40

How do you declare a bitset?

Answer 40

std::bitset<8> my_empty_byte;

Question 41

How do you declare and initialise a bitset with a value?

Answer 41

std::bitset<8> my_byte(128);

Question 42

How do you declare and initialise a bitset with a hexadecimal?

Answer 42

std::bitset<8> my_byte(0x0F);

Question 43

How do you declare and initialise a bitset with a binary value?

Answer 43

std::bitset<8> my_byte(std::string(“00110011”));

Question 44

How do you print bitsets?

Answer 44

std::cout &laquo_space;my_byte &laquo_space;std::endl;

Question 45

How do you clear a bit toa 0?

Answer 45

my_byte.reset(7);

Question 46

How do you set a bit to a 1?

Answer 46

my_byte.set(3);

Question 47

How do you flip a bit>

Answer 47

my_byte.flip(3);

Question 48

How do you access a single bit?

Answer 48

my_byte[5];

my_byte.test(0);

Question 49

What are the bit-wise operations?

Answer 49

AND = &
OR = |
XOR = ^
NOT = ~
Example:
std::bitset<4> = z = a | b;