C Program to calculate the factorial of a number using recursion

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In this example, you will learn how to find the factorial of a non-negative integer entered by the user using recursion.

To understand this example, you should be familiar with the followingC Programming LanguageTopic:

• C Function

• C User-defined function

• C Recursion

The factorial of a positive number n is given by the following formula:

factorial of n (n!) =　1　*　2　*　3　*　4　*...　　*　n

The factorial of a negative number does not exist. The factorial of 0 is1.

In this example, you will learn how to use recursion to find the factorial of a number. Visit this page to learn howFactorial using loop.

Factorial using recursion

#include<stdio.h>
long int multiplyNumbers(int n);
int main() {
　　　　int n;
　　　　printf("Enter a positive integer: ");
　　　　scanf("%d", &n);
　　　　printf("%d factorial = %ld", n, multiplyNumbers(n));
　　　　return 0;
}
long int multiplyNumbers(int n) {
　　　　if (n>=1)
　　　　　　　　return n*multiplyNumbers(n-1);
　　　　else
　　　　　　　　return　1;
}

Output the result

Enter a positive integer:　6
6　factorial =　720

Suppose the user entered6.

Initially, multipleNumbers() is called from main() and the6as a parameter.

Then, pass5is passed to multipleNumbers() (recursive call). In each recursive call, the value of parameter n is reduced1.

When the value of n is less than1There is no recursive call, and the factorial is finally returned to the main() function.

Comprehensive Collection of C Programming Examples