This document discusses different types of loops in programming including nested loops. It provides examples of nested while loops, do-while loops, and nested for loops. The examples demonstrate how to print series using nested loops. Nested loops involve placing one loop inside another loop. The inner loop must start after the outer loop and end before the outer loop to ensure logical nesting. Code samples are provided for each type of nested loop to illustrate their usage.

1. PRESENTATION
By:-
Balwinder Singh

2. CONTENTS
 What is a Loop?
 Nested While loops.
 Do…..While loops.
 Nested For loops.
 Question.

3. WHAT IS A LOOP?
 A loop is a programming structure that
contains an executable block of code that
repeats so long as a given condition is
true/not true.
 Good programmers include a way to satisfy
the condition somewhere inside the
executable block.

4. TYPES OF NESTED LOOPS
 Nested While Loops.
 Do…..While Loops.
 Nested For Loops.
nested
loops

5. NESTED WHILE LOOPS
 WHILE loops may be nested, that is you
can put a WHILE loop inside another
WHILE loop.
 However, one must start the inner loop after
starting the outer loop and end the inner
loop before ending the outer loop for a
logically correct nesting.

6. EXAMPLE:- NESTED WHILE LOOPS
To print the following series:-
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5

7. EXAMPLE:- NESTED WHILE LOOPS
#include<stdio.h>
#include<conio.h>
main()
{
int r=1,c=1;
while (r<=5)
{
c=1;
while(c<=r)
{
printf(“%d”,c);
c++;
}
printf(“n”);
r++;
}
getch();
}

8. DO……WHILE LOOP
 Executes the loop statement once and then
repeats the loop statement until the condition
is zero (false).
 Starts with a do statement and then tests the
repetition condition in the while statement at
the end of the loop.
Syntax:- do
{
statements;
}
while(condition);

9. LOGIC OF A DO….WHILE LOOPS
statement
true false
condition
evaluated
The while Loop

10. EXAMPLE:- DO….WHILE LOOP
#include<stdio.h>
#include<conio.h>
main()
{
int a;
do
{
printf(“Enter any number”);
scanf(“%”,&a);
if (a>=0)
printf(“Number is positive”);
else
printf(“Number is Negative”);
}
while(a!=0);
getch();
}
Accept any number from the user to print the number is
positive or negative.

11. NESTED FOR LOOPS
 A for loop can contain any kind of statement
in its body, including another for loop.
 The inner loop should have a different name
for its loop counter variable so that it will not
conflict with the outer loop.

12. EXAMPLE:- NESTED FOR LOOPS
Write a program to print the following series:-
1
2 3
4 5 6
7 8 9 10

13. EXAMPLE:- NESTED FOR LOOPS
#include<stdio.h>
#include<conio.h>
main()
{
int r,c,k=1;
for (r=1;r<=4;r++)
{
for (c=1;c<=r; c++)
{
printf(“%d”,k);
k++;
}
printf(“n”);
}
getch();
}

14. ANY QUESTIONS???