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(a)Describe the
following algorithm using a conventional flowchart
begin
input x
input y
z :=x+y
output z
end
[3 marks ]
Please
do not award half marks.
One mark the for correct representation of inputs and outputs; one
mark for the correct representation of calculation of z; one mark
for the correct representation of program flow.
(b)List three disadvantages
of conventional flowcharts.[3 marks ]
One mark should
be awarded for each disadvantage named (up to a maximum of three marks).
Examples include the following:
• The use of flowcharts can often lead to global, rather than
local, data being used in program design.
• The logic design tends to be intertwined, resulting in difficult
tracing and testing.
• There is no effective control as a esult of no superior/subordinate
relationship.
• Flowcharts do not help in partitioning a system to allocate
different parts to different team members. Other valid answers should
also receive credit.
[3 marks ]
(c)What are structured flowcharts
[2marks ]
Structure flowcharts are graphical tools that force designers to design
and structure software which is top-down (1 mark)and modular (1 mark).
Other valid answers should also receive credit. [2 marks ]
(d)Describe the following
parts of an algorithm using structured flowcharts
(i)
input x
input y
[1 mark ]
One mark should be awarded for the correct representation of a sequence
process.[2 marks ]
(ii)
if x > y then
z :=x-y
else
z :=y-x
[2 marks ]
One mark should
be awarded for the correct structure; one mark should be awarded for
the correct contents.[2 marks ]
(iii)
Do While z > 10
z := z div 10
[2 marks ]
One mark should be awarded for the correct structure; one mark should
be awarded for the correct contents.[2 marks ]
(iv)Case
x =0 :output ‘0’
x =2 or x =4 or x =6 orx =8 :output ‘even’
x =1 or x =3 or x =5 orx =7 or x =9 :output ‘odd’
End Case
[2 marks ]
One mark should
be awarded for the correct structure; one mark should be awarded for
the correct contents.[2 marks ]
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