This document discusses control structures called repetitions or loops in programming. It describes three types of loops: while loops, do-while loops, and for loops. It provides examples of how to write each type of loop in C++ and explains how the counter variable is incremented or decremented with each loop iteration. Nested loops and loops with sentinel values are also mentioned.

1. Chapter 4: Control Structure –
Repetitions/Loops

2. Objectives
State the types of repetitions
Differentiate among three types of
repetitions
Build a simple program to solve a problem
using repetitions


3. 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.

6. 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.

9. 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

10. While loop
 #include<iostream.h>
 main()
 {
 int i=0;
 while ( i <= 5 )
 {
 cout<<"n Welcome to while statement";
 i++;
 }
 }

11. do – while loop
 #include<iostream.h>
 main()
 {
 int i=0;
 do {
 cout<<"n Welcome to while statement";
 i++;
 } while ( i <=5);
 }

12. For loop
#include<iostream.h>
main()
{
 int i;
 for (i=0; i<=5; i++)
 cout<<"n Welcome to while statement";
}

13. For loops with counter
 Sintaksis:
 for (pembolehubah = nilai_awalan; syarat;
pembilang)
 Blok arahan
 { senarai penyataan;
 :
 :

 }

14. 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

15. Nested Loop
In a nested loop, one loop referred to as
the inner loop and one is called the outer
loop.