CS-101

Lecture 10

Algorithm and Flow Chart Developing logic (Examples on

algorithm and flowchart) Department of Computer Science

College of Arts and Science

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Relational Operator

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Operator Description

> Greater than

< Smaller than

≤ Smaller than or Equal

≥ Greater than or Equal

= Equal

≠ Not Equal

If else structure

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• The structure is as followsIf condition then

true alternative else

false alternativeendif

If else structure

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isA>B

Print BPrint A

Y N

Print A Print B

Example (1)

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Step 1: Start.

Step 2: Input M1,M2,M3,M4

Step 3: GRADE (M1+M2+M3+M4)/4

Step 4: if (GRADE < 60) then

Print “FAIL”

else

Print “PASS”

endif

Example (2)

Write a algorithm to find out number is odd or even?• step 1 : start• step 2 : input number• step 3 : rem=number mod 2• step 4 : if rem=0 then• print "number even"• else• print "number odd"• endif• step 5 : stop

Mr.Mohammed Rahmath

Chapter 2- Visual Basic Schneider 7

What is a flowchart?

• Diagram that visually represents the steps that the program performs to arrive at a solution.

• A popular logic tool used for showing an algorithm in graphical form.

Chapter 2- Visual Basic Schneider 8

Continue flowchart• Programmer draws flowchart before coding.• Most common flowchart symbols are:

– Flowline: indicates flow of logic. (arrow )

– Terminal: represents beginning or end of task (oval )

– Input/Output: represents input or output operations (parallelogram )

– Processing: data manipulation operations (rectangle )

– Decision: used for logic or comparison operation (diamond )

Chapter 2- Visual Basic Schneider 9

Example of Flowchart:Start

Initialize counterand sum to 0

Are there more data?

Get next grade

Increment counter

Add grade to sum

Yes

No

Average=sum/counter

Finish

This is a program to insert grades and calculate the average

Print the average

Cont..

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PRINT“PASS”

START

InputM1,M2,M3,M4

GRADE(M1+M2+M3+M4)/4

GRADE<60

PRINT“FAIL”

STOP

YN

Print “Fail”Print “Pass”

Example (2)

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Write an algorithm and draw a flowchart that will read the two sides of a rectangle and calculate its area.

Pseudocode • Input the width (W) and Length (L) of a

rectangle• Calculate the area (A) by multiplying L with W• Print A

Thank you for your attention

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Lecturer : Aasd Abd Elrashid