slide 07a - control structure_selection

8/10/2019 Slide 07a - Control Structure_Selection

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Computer Science Department FTSM

Control Structure:Selection(Part 1)

Knowledge:

Understand various concepts of selection control structure

Skill:

Be able to develop a program containing selection control structure


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TK1913-C Programming 2

Selection Structure

Single

Selection

Double Selection

Multiple

Selection


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Single SelectionPseudocode Structure

step a

if start

step m

step n

end_ifstep x


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Single Selection

Step a

condition Step m

Step n

Step x

true

false

Step a

condition Step m

Step n

Step x

true

false


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ExerciseDevelop an algorithm for the following problem:

A system to check/verify the eligibility of a person to voteduring the election is going to be developed. The input for

the system is the persons age.

If the age is greater than 20 years old, then display Youare eligible to vote and Your age is years oldmessages.

If the age is less than 20 years old, display Your age is years old message only.


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Exercise - Answer

true

false

You are

eligible to vote

age

start

end

Your age is

years old

age > 20

true

false

You are

eligible to vote

age

start

end

Your age is

years old

age > 20

Assume the age is

12 years old

12 > 20 ?

FALSE !

Your age is 12 years

old


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Something to ponder

the age is 37years old?What if ..

What about 20years old?


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Lets recap Pseudocode Structure

step a

if start

step m

step n

end_ifstep x

Single Selection

Double selection has similar

structure except that


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Double SelectionPseudocode Structure

step a

if startstep mstep n

end_if

else start

step xstep y

end_elsestep z

additional

steps at the

bottom


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Double SelectionStep a

condition Step m

Step n

Step z

true

false

Step x

Step y

Step a

condition Step m

Step n

Step z

true

false

Step x

Step y


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ExerciseDevelop an algorithm for the following problem:

A system to check/verify the eligibility of a person to voteduring the election is going to be developed. The input for

the system is the persons age.

If the age is greater than 20 years old, then display Youare eligible to vote and Your age is years oldmessages.

If the age is less than 20 years old, display You are noteligible to vote and Your age is years oldmessages.


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Exercise - Answer

true

false

You are

eligible to vote

age

start

end

Your age is

years old

age > 20

Verify this

flowchart !

You are not

eligible to vote


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Lets recap

Pseudocode Structure

step a

if start

step m

step n

end_ifstep x

Single SelectionPseudocode Structure

step a

if startstep mstep n

end_if

else start

step xstep yend_elsestep z

Double Selection

Guesshow does multiple

selection look like ?


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Multiple Selection

Pseudocode Structure (Multi-way if)

step a

if startstep m

end_if

if start

step nend_if

step z


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Multiple Selection

Step a

Condition1 Step m

Step n

Step z

true

false

Condition2

true

false

Step a

Condition1 Step m

Step n

Step z

true

false

Condition2

true

false


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Multiple Selection

Pseudocode Structure (Cascaded if)

step a

if start

step mend_if

if startstep n

end_if

else startstep x

end_elsestep z


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Multiple Selection

Step a

Condition1 Step m

Step n

Step z

true

false

Condition2true

false

Step x

Step a

Condition1 Step m

Step n

Step z

true

false

Condition2true

false

Step x


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ExerciseDevelop a flowchart for the following problem.

Given a mark, determine its grade based on the

table below:

74 < mark < 100 grade = A64 < mark < 75 grade = B

54 < mark < 65 grade = C39 < mark < 55 grade = D0 < mark < 40 grade = E

others error message


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End of Lecture 7 (Part 1)

Yes !! Thats all?Whats next???

PART 2on the way relax !

slide 07a - control structure_selection

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