1. UNIVERSITI TUN HUSSEIN ONN MALAYSIA
FACULTY OF MECHANICAL AND MANUFACTURING ENGINEERING
BTI 10202: COMPUTER PROGRAMMING
LAB 6 : Control Statements – Part 2 (Loops)
NAME : _____________________________
MATRICS NO.: _______________ DATE : _____ MARK
Objectives: Students be able to develop a repetition statements or program by using the iteration
structure (loops).
i. while loop statement
ii. do…while loop statement
iii. for loop statement
Theory:
a. while Example:
i. Syntax of while loop (one statement): /*Total up from marks 1 to marks 5.*/
while (condition- Code to execute while the while(count<=5) /* count from 1 until 5*/
condition is true) {
{ printf(“Key in the marks (%d) =”,
Statement; count);
} scanf(“%d”, &marks);
total=total+marks; /*add the marks
ii. Syntax of while loop (> one statement): one by one*/
while(condition- repeated until becomes false) count+=1; /*add the count*/
{ }
Statement 1;
Statement 2;
:
:
Statement n;
}
b. do…while loops are useful for things that want to loop at Example:
least once /* Total up from marks 1 until marks 5*/
Notice that the condition is tested at the end of the block do
instead of the beginning, so the block will be executed at {
least once printf(“Key in the
Syntax of do…while loop: marks(%d)=”,count);
do scanf(“%d”, &marks);
{ total=total+marks; ‘* total up the
Statement 1; marks one by one*/
: count+=1; /*add count*/
1

2. : }
Statements n; while(count<=5); /*repeat until count
} reach 5*/
while(condition);
c. for condition tells the program that while the conditional Example:
expression is true the loop should continue to repeat /*Total up from marks 1 until marks 5*/
itself. for(count=1;count<=5;count+=1)
Syntax of for loop: /*can write as ++count*/
for(initial value; condition; update counter) {
{ printf(“key in the
Statement(s); marks(%d)=”,count);
} scanf(“%d”, &marks);
total=total+marks; /* total up the
marks one by one*/
}
Flowchart for loop structures
d. Nested loops
Example:
#include<stdio.h>
#include<conio.h>
main()
{
int row,column,num;
do
2

3. {
printf(“nEnter the number of row of your triangle (1-30 only):n”);
scanf(“%d”,&num);
}
while(num<=0||num>30); /*cannot more than 30 or less than 0*/
printf(“Your trianglen”);
for(row=1;row<=num;++row)
{
printf(“n”);
for(column=1;column<=(row*2-1);column++)
{
printf(“*”);
}
}
getch();
}
Exercise:
1. What is the output of following ‘for’ loop source code?
#include<stdio.h>
#include<conio.h>
Output
main()
{
int i;
printf("This is a for loopn");
for(i = -5; i <= 0; i = i +1)
printf("%d ", i);
getch();
}
3

4. 2. Rewrite the ‘for’ loop program in Exercise 1 using ‘while’ loop statement to give the same
output.
While statement
3. Type the example source code for the nested loops (at theory: d section) and observe the
output. Explain the program in detail.
Output:
4

5. 5