Chapter 4: Control Structure –

Repetitions/Loops

Objectives

State the types of repetitions

Differentiate among three types of

repetitions

Build a simple program to solve a problem

using repetitions

pretest Repetitions structure

The expression (syarat) is evaluated, before the loop body is executed.

If the result of evaluation is true. the loop body is executed. Following this, control goes back to the expression and is evaluated again. This continues until the expression computes to a value of false.

If the expression produce of false, the loop body is bypassed and the program control drops down to the statement.

Posttest repetition statement

First executes the loop body and then

computes the expression (syarat).

If the expression is true, the loop body is

executed again; otherwise the repetition

terminates.

Repetitions with counter value (nilai

pembilang)

Nilai Pembilang Hasil dari pelaksanaan arahan nilai pembilang

i++ Nilai pembilang iaitu i ditambah dengan satu

i-- Nilai pembilang i dikurangkan dengan satu

i+=2 Nilai pembilang i ditambah dengan 2

i*=2 Nilai pembilang i didarab dengan 2

While loop

#include<iostream.h>

main()

{

int i=0;

while ( i <= 5 )

{

cout<<"\n Welcome to while statement";

i++;

}

}

do – while loop

#include<iostream.h>

main()

{

int i=0;

do {

cout<<"\n Welcome to while statement";

i++;

} while ( i <=5);

}

For loop

#include<iostream.h>

main()

{

int i;

for (i=0; i<=5; i++)

cout<<"\n Welcome to while statement";

}

For loops with counter

Sintaksis:

for (pembolehubah = nilai_awalan; syarat; pembilang)

Blok arahan

{ senarai penyataan;

:

:

}

Loops with sentinel value

we don’t know the number of loops will

execute.

For example, we don’t know how many

items bought by customer.

Refer to Rajah 4.8 page# 62

Nested Loop

In a nested loop, one loop referred to as

the inner loop and one is called the outer

loop.