T7 - Arrays and Subroutines

Question 1

Arrays:

Answer 1

data structure that allows you to hold many items of data which is referenced by one identifier

Question 2

To find an array length do

Answer 2

variable.len for python
variable.length in pseudocode

Question 3

arrays and data types stored

Answer 3

All items of data in the array must be of the same data type

Question 4

arrays works how

Answer 4

Information can be read from or added to the array using the index number

Question 5

array indexes

Answer 5

Indexes in most languages start at 0 not 1

Question 6

Arrays lengths

Answer 6

have fixed lengths

Question 7

Linear search,

Answer 7

• each item is examined in sequence until the item is found or the end of the list is reached

Question 8

Bubble sort:

Answer 8

• Each item in a list is compared to the one next to it, and if it is greater, they swap places
• At the end of one pass through the list, the largest item is at the end of the list
• this is repeated until the items are sorted

Question 9

how to loop arrays

Answer 9

By using a FOR loop we can easily loop through an array.

Question 10

Subroutines:

Answer 10

allow code that you intend to use a number of time to be grouped together under one name

Question 11

eg of subroutines

Answer 11

Both functions and procedures are subroutines

Question 12

features of subroutines

Answer 12

Values can be passed to both procedures and functions

Question 13

functions and outputs

Answer 13

Functions will return a value after processing has taken place

Question 14

procedures

Answer 14

Procedures - execute code in a subroutine, but they don’t return anything

Question 15

arguements

Answer 15

Both functions and procedures have arguments = eg (“Hello”) or (1,6)

Question 16

Parameters:

Answer 16

sum(a, b)
a and b are known as parameters

Question 17

Pros of subroutines:

Answer 17

• They are useful to break up a large program into self-contained units
• Each subroutine can be tested separately to make sure it works correctly
• Many programmers can work on a large program at the same time, cutting down development time
• can be re-used in other programs
• can be stored in a subroutine library and used in different programs if required
• Program maintenance is easier – if requirements change then just the affected subroutines need to be modified

Question 18

“scope” of a variable, constant, procedure or function

Answer 18

defines the parts of the program in which it is recognised and can be used

Question 19

Local variables:

Answer 19

only exist while the subroutine is executing
They are only accessible within the subroutine

Question 20

Global variables:

Answer 20

are accessible anywhere in the program

Question 21

global variable in pseudocode =

Answer 21

global score

Question 22

Global and local constants:

Answer 22

Constants follow the same rules as variables
A constant declared in the main program can be seen and used, but not changed, anywhere else

Question 23

Pros of local variables:

Answer 23

keep a subroutine self-contained,
it can be used in any program without variable names conflicting with those used in the calling program

Question 24

python length number of array

Answer 24

variable.len