8.2 Looping 1 Feb 2017

APPROACH IN PROBLEM SOLVING- Control Structure

• At the end of lesson, student should able to :- explain the purpose of looping control structure- apply looping control strcuture in problem soving

- LOOPING / REPETITION

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LOOPING CONTROL STRUCTURE

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The essentials of Looping

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Applying Algorithm in Looping construct

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Initial value

while (condition)

statement(s) to be executed if

condition is TRUE

Updating value

False

True

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end

Start


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bil=1

while (bil≤4)

bil=bil+1

False

True

Print “hello world”

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end

Start


Bil ConditionBil≤4

Output Updating, bil=bil+1

1 T Hello world 2

2 T Hello world 3

3 T Hello world 4

4 T Hello world 5

5 F

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bil=4

while (bil≥1)

bil=bil-1

False

True

Print “hello world”

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end

Start


Bil ConditionBil≥1

Output Updating, bil=bil-1

4 T Hello world 3

3 T Hello world 2

2 T Hello world 1

1 T Hello world 0

0 F

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bil=1

while (bil≤5)

bil=bil+1

False

True

Input width, height

area = width x height

Print area

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end

Start


Bil ConditionBil≤4

Input width, height

area=width x height

Output; area

Updating, bil=bil+1

1 T 2

2 T 3

3 T 4

4 T 5

5 T 6

6 F

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Applying algorithm in looping structure

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End if

bil=1

while (bil≤20)

bil=bil+1

False

True

Input mark

Print “status Pass”

if (mark≥50)

Print “status Fail”

True

False

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end

Start

Applying algorithm in looping structure

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bil=1

while (bil≤x)

bil=bil+1

False

True

Input radius

area = 22/7 x radius x radius

Print area

Input x

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end

Start

Sentinel-controlled loop

✓ A sentinel variable is initialized to a specific value. The while loop continues until, through some action inside the loop, the sentinel variable is set to a predefined termination value.

✓ In the following example the user is asked to type characters at the keyboard, which are then appear on the screen, then press the Enter key when done.

✓ Pressing the Enter key sets the char variable answer to the ‘N’ character (defined by the special character ‘N').

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Answer = Y

while (answer ≠ N)

False

True

Print “I Love KMPK”

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end

Start

Input answer

Accumulating in problem solving

2 1 2 1

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bil=1, sum = 0

While (bil≤50)

bil=bil+1

False

True

Input number

sum=sum + number

Print sum

* sum printed when condition is FALSE. Its because, when the condition is FALSE, that means all the 50 numbers already calculated by program

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end

Start


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bil=1, sum = 0

while (bil≤50)

bil=bil+1

False

True

Input number

sum=sum + number

Print sum , average

* Average printed when condition is FALSE. Its because, average can calculated when all the number were input

average=sum/50

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end

Start

Summary looping- basic loop- sentinel-controlled loop- accumulating loop

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bil=1

while (bil≤4)

bil=bil+1

False

TruePrint

“hello world”

end

Start

Basic loop

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end

Start


Answer = Y

while (answer ≠ N)

False

True

Print “I Love KMPK”

Input answer

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end

Start

Accumulating loop

bil=1, sum = 0

While (bil≤50)

bil=bil+1

False

True

Input number

sum=sum + number

Print sum

8.2 Looping 1 Feb 2017

Education