Sub-programs

Question 1

sub-program/subroutine

Answer 1

a self contained sequence of program instructions that performs a specific task

Question 2

When are sub programs called?

Answer 2

whenever they need to carry out their specific function

Question 3

uses of sub programs (5)

Answer 3

-allows the production of structured code

-makes programs shorter/more efficient
the code is written once and called as many times as needed

• program code is easier to read and test
• shortens development time of a program
• makes code more readable

Question 4

function

Answer 4

a subroutine that returns a value to the main program when it is called

they have to be defined:
function functionName(parameters)
    code
    return
end function

Question 5

procedure

Answer 5

a sub-program that carried out a specific task but does not return a value to the main program
they could do something such as print a message to the user

they have to be defined:
procedure procedureName(parameters)
code
endprocedure

Question 6

parameters

Answer 6

where values passed to the function from the main program are stored

Question 7

local variable

Answer 7

variables used within the subroutine and not in the main program

Question 8

The following program included a sub program.

1
2     print("Hello " + first + " " + last)
3
// the following is the main program
4 name1 = input("Enter first name.")
5 name2 = (input("Enter surname")
6 salutation(name1, name2)

a) Complete the program by writing the code for:
i) line 1 [2]
ii) line 3 [1]

b) state one parameter used in the program [1]

Answer 8

a)

i) procedure salutation(first, last)
ii) endprodcedure

b) first or last

Question 9

Write a subroutine that takes in a sentence entered by the user and returns the number of characters excluding spaces. [5]

Answer 9

function analysis(text)
    total = 0
    for index = 0 to text.length - 1
        if text(index) != " " then
            total = total + 1
        endif
    next index
    return total
endfunction

//main program
sentence = input("Please enter the sentence.")
characters = analysis(sentence)
print(characters)

Question 10

global variable

Answer 10

a variable used in the main program

Question 11

should you use the same names for local and global variables?

Answer 11

no, as it would be easy to mix them up

Question 12

The following is part of a program and a function to return the area of a rectangle.

function rectangle (length, width)
    area = length * width
    return area
endfunction

//main program
rectArea = rectangle(rectLength, rectWidth)
print(rectArea)

a) List two global variables [2]
b) list two parameters [2]
c) state a local variable [1]

Answer 12

a) rectArea, rectLength, rectWidth
b) length, width
c) area

Question 13

A student is creating a computer version of a board game during which each user has to shake two dice and find the total.

Create a function that will simulate the dice throws and return the total to the main program. [4]

Answer 13

(the random command is not in the OCR pseudocode, but any command that can be understood by a competent person can be used)

function dice()
    dice1 = random(1, 6)
    dice2 = random(1, 6)
    total = dice1 + dice2
    return total
endfunction