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Exercise 2.4

1. Define what is algorithm?Algorithm is a procedure for solving a problem in terms of the actions to be executed and the

order in which these actions are to be executed.

2. In what kind of form the algorithm can be written?Algorithm can be written in pseudo codes or flowchart.

3. List out the basic control structures and briefly explain each of it.i. Sequence: is a series of statements that execute one after another,ii. Selection (branch): is used to execute different statements depending on certain

conditions. Eg: IF condition THEN statement1 ELSE statement2,

iii. Repetition (loop): is used to repeat statements while certain conditions are met.

4. Briefly explain three type of error.

i. Syntax error: Errors in spelling and grammar (syntax).Caught by compiler.ii. Run-time error: Code does something illegal when it is run (hence runtime). Example,divide by zero.

iii. Logic error: Do not get error messages with logic errors. The only clue to the existence oflogic errors is the production of wrong solutions.

5. List out and briefly explain the common flowcharts symbol?

Symbol Name Discripsion

Terminal/Terminator The beginning or end of aprogram

Process Computation or datamanipulation. Indicates anytype of internal operation

Data Used for any Input / Output(I/O) operation.Indicates that the computer isto obtain dataor display output or results

Decision A program branch point

On-page reference/Connector

An entry to, or an exit from,another part of the flow chart

Flow lines Connecting the flowchartssymbols. Shows direction offlow.

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7. Write the analysis ( input, output and process/formula ) and design (pseudo code andflowchart) for problems below:

7.1. A program will read four integers from the keyboard, calculates their sum, and then printsthe numbers with the sum.

Input= Four integers from the keyboardOutput= The numbers with the sum.Process= n1+n2+n3+n4

Pseudo code

1. Start

2. Set sum = 0

3. Read four integers: num1, num2, num3 and num4

4. Calculate sum = num1 + num2 + num3 + num4

5. Print sum

6. End

Flowchart

Start

Sum = 0

Read four

integers:

num1, num2,

num3 and

Sum = num1 + num2 +num3 + num4

Print Sum

End

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7.2. Represent the processes/activities/sequences of sending a message using mobilephone.

Input= Message that we want to sentOutput= Message delivered or message sending failed.Process= Sending the message

Pseudo code

1. Start

2. Input text message, phone number of recipient

3. Send message

4. If sending successful

Print Message sent

5. Else

If sending failed

Print Message sending failed

6. End

Flowchart

Start

Input text

message,

phone numberof recipient

Send message

Doessending

successful?

Print

Message

sent

PrintMessage

sending failed

End

Yes

No

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7.3. Warong Abu provides a menu of nasi lemak for breakfast. The price of the items are:

Nasi Lemak + sambal + ikan bilik + timun RM1.50Option:Sambal sotong RM1.50Sambal udang RM1.00

Fried/ Boiled Egg RM0.60Each customer may order nasi lemak with any option. Calculate the price of each order.

Input= Option that was selectedOutput= Total priceProcess= Calculate the total price

Pseudo code

1. Start

2. Set Price=1.50

3. Read Options

4. If no option selected,

Print Price

5. Else, If Option is sambal sotong,

Calculate Price=Price+1.50

Print Price

6. Else, If Option is sambal udang,

Calculate Price=Price+1.00

Print Price

7. Else, If Option is fried/boiled egg,Calculate Price=Price+0.60

Print Price

8. End

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Flowchart

Start

Set Price=1.50

Read

Option

Is there

any option

selected?

PrintPrice

If sambal

sotong

selected

End

If sambal

udang

selected

If

fried/boiled

egg selected

Price=Price+1.50

Price=Price+1.00

Price=Price+0.60

Yes

Yes

Yes

Yes

No

No

No

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7.4.The program will print A for exam marks greater than or equal to 80, Print B for marks

in the range 65 to 79, Print C for marks in the range 50 - 64, Print D for marks in therange 40 to 49 and E for all other marks.

Input= Read markOutput= Print A or B or C or D or E

Process= If 100 MARKS 80, Print A

If 79 MARKS 65, Print B

If 64 MARKS 50, Print C

If 49 MARKS 40, Print D

If 39 MARKS 0, Print E

Pseudo code

1. Start

2. Read MARKS

4. If 100 MARKS 80

Print A

5. Else

If 79 MARKS 65

Print B

6. Else

If 64 MARKS 50

Print C

7. Else

If 49 MARKS 40

Print D

8. Else

If 39 MARKS 0

Print E

9. End

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7.5. The program will calculate the perimeter of a circle. The radius is 7.With the perimeter

formula (2*radius*PI), print the output of the perimeter for the circle. Value of PI is 3.142.

Input= set the radius of circle

Output= The perimeter for the circleProcess= 2*radius*PI

Pseudo code

1. Start

2. Set Perimeter=0, PI=3.142

3. Input radius=7

4. Calculate Perimeter=2*radius*PI

5. Print Perimeter

6. End

Flowchart

Start

Set Perimeter=0,

PI=3.142

Input

radius=7

Calculate

Perimeter=2*radius*PI

Print

Perimeter

End

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Flowchart

Start

Read

MARKS

If

100MARKS

80

If

79MARKS

65

If

64MARKS

50

If

49MARKS40

If

39MARKS0

Print

A

Print

D

Print E

Print C

Print B

End