C Program for calculating factorial of a number using recursion

C Program for calculating the factorial of a number using recursion

In this tutorial, we will discuss the C  Program for calculating the factorial of a number using recursion

There are many ways to calculate factorial using C language and one of this given below – Using the recursive function in C language

 

In this article, we are going to learn how to calculate factorial of a number using the recursive function  in C programming language

Factorial is a product of all positive descending integer begins with a specified number (n) and calculates up to one

 

Example

factorial of 5 is

5!=5*4*3*2*1=120

 

factorial of 4 is

4!=4*3*2*1=24

 

factorial of n is

n!=n*(n-1)*....2*1

Program

This program allows the user to enter a positive integer number and it calculates the factorial of the given number using the recursive function in C language

Program

#include <stdio.h>
#include <stdlib.h>
int factFind(int);//function prototype
int main()
{
    int num;
    //ask input from the user
    printf("Enter a positive integer\n");
    //given value is stored in num variable
    scanf("%d",&num);

    //calling the findFact() function- user-defined
    int factorial=factFind(num);

    //displaying factorial of the given number
    printf("factorial of %d=%d",num, factorial);
    getch();
    return 0;
}
int factFind(int num){//function definition
if(num>=1)
    //function calling itself recursively
    return num*factFind(num-1);
else
    return 1;
}

The above code is executed. it produces the following result

Enter a positive integer
7
Factorial of 7=5040

Approach

• The program requests to enter a number from the user
• The entered number  is stored in the num variable
• when The findFact() is called from the main method, the num(user input) is passed as an argument to the function findFact()
• If the num(given number) is greater than or equal to 1, the number is multiplied with the result also  the num(num-1) is passed as an argument again
• In each and every recursive call, the value of the argument num is decreased by 1(num-1) until the num becomes less than 1(num>=1)
• When the value of num is less than 1, The control skips the recursive function and comes to end the recursive call

 

 

To clearly understand this article, you should have the previous knowledge of the following C programming subject

The recursive function in C language

The function  in C language

If statements in C language

 

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