This document explains recursion in programming, highlighting how a function can call itself, and emphasizes the importance of a base case. It provides example programs for calculating the sum of numbers and the factorial of a nonnegative integer using recursion. The factorial example illustrates the calculation of 5!, resulting in an output of 120.

1. Simple program recursion
simple program finding
factorial
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2. RECURSION
• Recursion is a function in
which a function calls itself
• Recursion make large
program into small program
• It has a condition called base
case
• The base which tell a
recursion function where to
stop

3. Example program for recursion
• #include<stdio.h>
• Int sum(int n);
• Int main() {
• Int number ,result;
• Printf(“enter a positive integer“);
• Scanf(“%d”,&number);
• Result=sum(number);
• Printf(“sum=%d”,result);
• Return 0;
• }
• Int sum(int n) {
• If(n!=0)
• Return n+sum(n-1);
• Else
• Return n;
• }

4. FACTORIAL
• The factorial of a
nonnegative integer
n,written n!(and pronounced
“n factorial”), is the product
• Recursion definition of the
factorial function
• N!=n*(n-1)
• Example
• 5!=5*4*3*2*1
• 5!=5*(4!)

5. Simple program on factorial
• #include<stdio.h>
• #include<conio.h>
• Int factorial(int);
• Int main()
• {
• Int n;
• Printf(“n enter number”);
• Scanf(“%d”,&n);
• Answer=factorial(n)
• Printf(“factorial=%d”,answer);
• getch()
• Return 0;
• }

6. • Int factorial(int n)
• {
• Int f;
• If(n==0)
• Return 1;
• Else
• F=n*factorial(n-1);
• Return f;
• }

7. output
• Enter a number 5
factorial is 120

8. THANK YOU