1. Algorithm & Flow Charts Decision Making and Looping
Presented By Manesh T Course:1090 CS

2. Definition Loops are used to represent repetitive statements
In looping, a sequence of statements are executed until some conditions for termination of the loop are satisfied.
A program loop therefore consists of two segments,
body of the loop
control statements.

3. Structure of Loops Exit Controlled Loop Entry Controlled Loop Exit

4. Types of Loops For Loop While Loop Do-While Loop
Before studying Loops, let us study how to write algorithm and flowchart of loop based programs

5. Algorithm examples –loops Problem1: To print first n Numbers Problem2: To print sum of first “n” Numbers Problem3: To print all even numbers up to “n”
Study all the above Problems Well.

6. Problem: To print first n Numbers
Step 1: Start Step 2: Read n,i=1 Step 3: Is i<=n then goto step 4 else goto step 6 Step 4: Print i Step 5: i=i+1, goto step 3 Step 6: Stop

7. Problem: To print sum of first “n” Numbers
Step 1: Start Step 2: Read n,i=1,sum=0 Step 3: Is i<=n then goto step 4 else goto step 6 Step 4: sum=sum+i; Step 5: i=i+1, goto step 3 Step 6: Print sum Step 7: Stop

8. Problem: To print all even numbers up to “n”
Step 1: Start Step 2: Read n, i=0 Step 3: Is ( i<=n) then goto step 4 else goto step 6 Step 4: Is (i%2=0) then print “i” Step 5: i=i+1, goto step 3 Step 6: Stop

9. Flowchart examples –loops Problem1: To print first n Numbers Problem2: To print sum of first “n” Numbers Problem3: To print all even numbers up to “n”
Study all the above Problems Well.

10. Problem: To print first n Numbers
Output:
N=5 1 2 3 4 5
Start
Read N, I=1
Is I< =N No
Yes
Print I
I=I+1
Stop

11. Problem: To print sum of first “n” Numbers
Start
Read n, i=1,sum=0
Is i<=n No
Yes
Print sum
Sum=sum+i
i=i+1
Stop

12. Problem: To print all even numbers up to “n”
Output:
N=10 2 4 6 8
Start
Read n, i=1,sum=0
Is i<=n No
Yes
i=i+1
Is i%2=0 No
Yes
Print i
Stop

13. Structure of While , Do While Loop

14. Structure of for loop

15. C Programs examples –loops Problem1: To print first n Numbers
Let us study how to write above program using while, Do-while and For loops

16. Problem: To print first n Numbers
#include<stdio.h> void main() { int n, i=1; printf(“Enter n”); scanf(“%d”,&n); while(i<=n) printf(“%d”, i); i++; }
Program Using while loop

17. Problem: To print first n Numbers
#include<stdio.h> void main() { int n, i=1; printf(“Enter n”); scanf(“%d”,&n); do printf(“%d”, i); i++; }while(i<=n); }
Program Using do-while loop

18. Problem: To print first n Numbers
#include<stdio.h> void main() { int n,i; printf("Enter n:\n"); scanf("%d",&n); for(i=1;i<=n;i++) printf("%d\n",i); }
Program Using for loop

19. Tutorial/Model Programs
Print first N numbers
Print sum of first N Numbers
Print all even numbers upto N
Print all odd numbers upto N
Print sum of even numbers up to N
Print sum of odd numbers up to N
Print sum of even and sum of odd numbers up to N

20. Assignment 3 C program to print sum of even numbers upto “n”
C program to print sum of odd numbers upto “n”
C program to average of first n numbers