CS Week 5- Arrays and Intro to Pointers

Question 1

array

Answer 1

an ordered list of items of a given data type

Question 2

element

Answer 2

each item in an array

Question 3

declaration of an array

Answer 3

dataType arrayName [numElements];

Question 4

index type

Answer 4

int type only

Question 5

to check if index is valid

Answer 5

if (nth >= 1 && nth <= 5) { }

Question 6

iterate how many times through a loop

Answer 6

the size of the array that you should keep track up

Question 7

array initilization

Answer 7

int myArray[3] = {5, 6, 7};

Question 8

array vs vector
declaration and accessed and differences

Answer 8

Array -
Declaration: int myList[#];
Accessed: myList[i];
Vector-
Declaration: vector<int> myList(#)
Accessed: myList.at(0);</int>

Arrays have simpler syntax but do not have .size() feature
Vectors are safer

Question 9

an array as a paramter

Answer 9

uses the [], but argument does not
passes in an array

Question 10

reversing an array

Answer 10

loop numElements/2 times
tempVal = a[i];
a[i] = a[numElements - 1- i];
a[numElements - 1-i] = tempVal;

Question 11

two dimensional array

Answer 11

int myArray [R][C]

Question 12

row major order

Answer 12

compiler maps 2-dimensional array elements to one-dimensional memory, each row following the previous row

Question 13

two-dimensional array initialization

Answer 13

int nums [2][3] = { {2,4,6}, {5,6,7} };
Or to make it more visible
int nums [2][3] = {
{2, 4, 6},
{5, 6, 7}
};

Question 14

access row n and column m

Answer 14

array[n-1][m-1]

Question 15

pointer

Answer 15

a variable that holds a memory address (rather than holding data)

Question 16

what does the data type of a pointer mean

Answer 16

the type of address that is held in the pointer

Question 17

declare and initialize it

Answer 17

int* pointer = &someVar;

Question 18

dereference operator

Answer 18

*
is prepended to a pointers variable name to retrieve the data to which the pointer variable points

Question 19

null pointer

Answer 19

When a pointer is declared, the pointer variable holds an unknown address until the pointer is initialized
Null means nothing
int* pointer = nullptr;

Question 20

check if null

Answer 20

in notes

Question 21

change the value of the variable that the pointer is pointing to

Answer 21

*p = 888;

Question 22

use/cout the pointer/the value the pointer is poitning to

Answer 22

cout &laquo_space;*p;

Question 23

other ways to dereference a pointer

Answer 23

*p = 44;

p[0] = 444;
p[-1]
go to where p is pointing and advance 0/-1 steps

p = p + 1
*p = 555;

*(p+1) = 8888;

Question 24

other ways to initialize a pointer

Answer 24

int* q = p + 5;
int* q = A + 5;
int* q = &(A[5]);
int* q = A;

Question 25

double pointer and const

Answer 25

int** pp = &p
pp points to the same place as p

int * const * const what;
-a const pointer to a const pointer to an int (what)
-can change the value of what you are pointing to

const int * const * const what;
can not change what the pointer is pointing to

Question 26

K, Meg, Gig, Tera

Answer 26

K = 2^10
Meg = 2 ^10 K = 2 ^20
Gig = 2 ^10 M = 2 ^ 30
Tera = 2 ^ 10 G = 2 ^ 40

Question 27

passing in an array or pointer into a funciton

Answer 27

int A[]

int* A
- no need for reference because * is one kinda

int* A, unsigned n;
let people know what passing in
n = offset if A is a pointer, size of pointer is a collection of data