This document discusses different types of looping structures in programming including entry controlled loops like while loops where the test condition is at the beginning, and exit controlled loops like do-while loops where the test condition is at the end. It provides examples of while and do-while loops, explaining that while loops use a counter variable to control the number of executions, whereas do-while loops always execute at least once before checking the condition.

1. LOOPING STRUCTURES

2. LOOPS
Entry Controlled
Loop
Exit Controlled
Loop

3. ENTRY CONTROLLED
LOOPS

4. EXIT CONTROLLED
LOOPS

5. Entry controlled
Test condition appears at the
beginning.
Control variable is counter
variable.
Each execution occurs by
testing condition.
Eg:
sum = 0;
n = 1;
while (n <= 10)
{
sum = sum + n*n;
n = n+ 1;
}
Exit controlled
Test condition appears at the end.
Control variable is counter &
sentinel variable.
Each execution except the first
one occurs by testing condition.
Eg:
do
{
printf(“Input a number.n”);
scanf("%d", &num);
}
while(num>0);

6. ENTRYCONTROLLED
LOOPS
for Statement
while
Statement

7. for STATEMENT

8. for STATEMENT

9. while STATEMENT

10. while STATEMENT

11. EXITCONTROLLED
LOOPS
do….while
Statement

12. do…while STATEMENT
Do while has a loop condition only that is tested
after each iteration to decide whether to continue
with next iteration or terminate the loop.

13. EXAMPLES(quicktime player reqd)