Repetition Cont

8/18/2019 Repetition Cont

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Repetition Structure

(continued)


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Counter-Controlled Loops

• Loops can be controlled using a

counter rather than a sentinel value

• These are called counter-controlled loops


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Miguel Music Company’s

ProgramThe sales manager at Miguel’s Music Company

wants a program that allows him to enter the

quarterly sales amount made in each threeregions: Region ! Region "! and Region #$ The

program should calculate the total quarterly

sales and then display the result on the screen$


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Miguel Music Company’s

Program• The program will use a counter to

ensure that the sales manager enterse%actly three sales amounts$

• &t will use an accumulator to total the

sales amount$


5/43

'ample (utput o)

Miguel Music Company’s Program


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'olution to Miguel Music Program

int sales, counter=1, total=0;

while (counter


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• +se)ul )or counter*controlled loop

• Format:%or( initialization; e&ression ; update )

{1 or ore stateents;

,o -

goes here

Required ;


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10/43

The %or Loop

• 1%pression 2condition3 / any C44

e%pression that is evaluated as )alse or

true$• &) the e%pression is true any statements in

the body o) the for loop are e%ecuted$

• &) the e%pression is )alse the loop will bee%ited! bypassing the body o) the for

loop$


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The %or Loop

• +pdate / represents any C44 statements

that ta0e place a)ter e%ecuting the loop

body$• +sually contains an e%pression that

updates the counter variable


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13/43

for and while loops

%or (int &=1;

&


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The %or Loop

• &n for loop! the variable is o)ten

declared and initiali.ed inside the )or

loop statement$

%or (int &=1; &


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%or Loop 'ample (utput


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'olution to %or Loop

%or (int &=1; &


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18/43

'olution to %or

'quare Loop

• !t is used )or tab 2must be place in coutstatement3

• cout55 6 7t 6


19/43

'olution to %or

'quare Loopcout


20/43

Re"iew o#

Pretest "s$ Posttest Loops• 8hether you use a while loop or for

loop! the loop body might never

e%ecute$• 9oth o) these loops are pretest loops /

loops in which the loop control variable

is tested be)ore the loop body ise%ecuted$


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Pretest "s$ Posttest Loops

• 'ometimes! you want to ensure that a

loop body e%ecutes at least once$

• That way! the code de)initely woulde%ecute one time even i) the loop was

never entered$

• n alternative is to use posttest loop /one in which the loop control variable is

test a)ter the loop body e%ecutes$


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Pretest "s$ Posttest Loops

• There)ore! the instructions in a posttest

loop will always be processed at least

once• 8hile the instructions in a pretest loop

may not be processed i) the condition

initially evaluates to )alse


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The $o4while Loop

• $o4while Loop / controls a loop that

tests the loop*continuing condition at

the end! or bottom! o) the loop$


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• $o4while: a posttest loop 2expression isevaluated a)ter the loop e%ecutes3

• Format:$o

{1 or more statements;

while (expression);

Notice the

required ;


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$o4while ;low o) Control

statement(s)

condition

false

true


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$o4while 'ample (utput


27/43

'olution to $o4while Loop

int &=1;

$o{

cout


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$o4while 'ample (utput


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8hich o) the )ollowing is )alse=

$ The while loop is a pretest loop$

"$ &n a )or loop! the loop body might nevere%ecute$

#$ The do*while loop controls a loop that

tests the loop*continuing condition at thetop o) the loop$


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nswer

3. The do-while loop controls a loop that

tests the loop-continuing condition at thebottom of the loop.


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,ested Loop

• loop that completely contains another

is an outer loop (row)$

• loop that )alls entirely within the body

o) another is an inner loop (column)$

• >ou can place one loop 2the inner! or

nested loop3 inside another loop 2the

outer loop3


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for and do-while

'ample (utput


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'olution to %or an$ $o4

while Loop$o{

%or (int &=1; &


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for and for

'ample (utput


37/43

'olution to for an$ for

Loop%or (int row=1; row


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Multiplication Table

'ample (utput


39/43

'olution to

Multiplication Table

cout


40/43

,ested for

'ample (utput

' l ti t


41/43

'olution to

,ested for

%or (int row=1; row


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%an& 'ou

Prepared by: Prof. LRQ Natividad


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%at in all tings!

od may e glori#ied?

Prepared *y: Pro#$ LR+ ,ati"idad

Date post:	07-Jul-2018
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