Lecture 3

Question 1

for a single-dimensional array, can you have different data types?

Answer 1

no, all elements must be the same type
ex) int array –> only ints allowed

Question 2

what is the sequence of elements in a single dimensional array?

Answer 2

contiguous aka ordered sequence
- no holes in the array, must be
elements at every index

Question 3

is the size/length of an array fixed?

Answer 3

yes, the number of elements (N) is set when the array is created
ex) int a[5];

Question 4

what index position is the first element in the array located at?

Answer 4

A[0]

Question 5

what index position is the last element in the array located at?

Answer 5

A[N - 1], where N is the number of elements

Question 6

single-dimensional array basic syntax

Answer 6

data_type name[size];
ex) int mol[5];

Question 7

if you don’t initialize your array with values, will it be assigned to 0?

Answer 7

no, it will be assigned to whatever is leftover in memory at those address locations
**best to initialize upon creation

Question 8

what happens in memory when you create an array and initialize it with values?

Answer 8

the right amount of memory will be allocated based on the size of the array and will be set to those values

Question 9

how do you calculate how many bytes are allocated on the stack for an array?

Answer 9

number of elements (size) * size of data type
ex) int a[5]
int = 4 bytes
size = 5 elements
4 * 5 = 20 bytes allocated

Question 10

how to find how many bytes are allocated on the stack for an array using code?

Answer 10

using sizeof( )
ex) int A[N];
int bytes = N * sizeof(int);

Question 11

does c have a length property?

Answer 11

no

Question 12

how to find the size of an array?

Answer 12

size = total # of bytes / size of data type
ex)
int size = sizeof(A) / sizeof(int);
- this returns the total number of bytes divided by the amount of bytes for each element –> gets size of array

Question 13

is there array bound checking in c?

Answer 13

no

Question 14

if you try to access an index in your array outside of the size of your array (int A[5]; –> say something like A[10]), what happens?

Answer 14

unpredictable behavior: may work, but a memory fault (aka segmentation fault) will likely occur
- memory access violation –> attempting to access a restricted area in memory

Question 15

multi-dimensional array basic syntax

Answer 15

data_type name [size1] [size2]…size[N];

Question 16

int A [2] [3];
how many rows and columns are there?

Answer 16

2 rows, 3 columns

Question 17

how to calculate the number of bytes allocated in memory for multi-dimensional array?

Answer 17

of bytes = # of elements * sizeof(data type)

Question 18

how to calculate the number of elements in a multi-dimensional array?

Answer 18

array[size1] [size2];
size1 * size2

Question 19

how to calculate the number of rows in a multidimensional array?

Answer 19

number of rows = total # of bytes / # of bytes in one row

ex)
int A[2] [3];
int rows = sizeof(A) / sizeof(A[0]);

Question 20

how to calculate the number of columns in a multidimensional array?

Answer 20

number of columns = # of bytes in one row / # of bytes in one element
ex)
int columns = sizeof(A[0]) / sizeof(int);

Question 21

is there a string data-type in c?

Answer 21

no, just a char array

Question 22

what must all char arrays be?

Answer 22

null terminated

Question 23

what is the null terminator?

Answer 23

‘\0’
- marks the end of the string
- also equal to integer 0

Question 24

what happens to characters after the null terminator in the array?

Answer 24

they are considered invalid, would not get printed if displayed on the console

Question 25

char string[5] = “abcd”;
char string[] = “abcd”;
char string[5] = {‘a’, ‘b’, ‘c’, ‘d’, ‘\0’}

which of the following are correct implementations?

Answer 25

all of them

Question 26

if you initialize this way:
char string[5] = {‘a’, ‘b’, ‘c’, ‘d’, ‘\0’}
do you have to include the null terminator?

Answer 26

YES, all other ways include it for you, but must add it if you initialize this way

Question 27

what is string.h?

Answer 27

string library, gives you access to all the functions in this string library

Question 28

what is strlen() ?

Answer 28

function included in the string library
- determines number of characters
- counts characters UP to null terminator

Question 29

does strlen() include the null terminator in it’s count?

Answer 29

NOO, counts characters up until null terminator

Question 30

char string[5] = {‘a’, ‘b’, ‘c’, ‘d’, ‘\0’};
printf(“%d\n”, strlen(string));

what is printed?

Answer 30

4
- abcd = 4 characters
- counts up until null terminator

Question 31

char string[5] = {‘a’, ‘b’, ‘c’, ‘d’, ‘\0’};
string[2] = ‘\0’;
printf(“%d\n”, strlen(string));

what is printed?

Answer 31

2
- ab = 2 characters
- counts up until null terminator @ index 2
- doesn’t include it in count or any char after it

Question 32

char string1[] = “brent”;
char string2[] = “david”;
string1 = string2;

does this work?

Answer 32

no, both of these variables point to a memory address –> will cause error
char arrays point to strings

Question 33

char string1[] = “brent”;
char string2[] = “david”;
strcpy(string2, string1);

what does strcpy do?

Answer 33

copies character by character from string1 into string2
string2 now equals “brent”