Write a C Program to check number is divisible by 11 and 9 using recursion

By | March 23, 2017

C Program to check whether number is divisible by 11 and 9 or not


Write a C Program to check whether number is divisible by 11 and 9 or not by recursion. Here’s simple Program that tests whether a number is divisible by 11 and 9 or not using Recursion in C Programming Language.


Recursion : :


  • Recursion is the process of repeating items in a self-similar way. In programming languages, if a program allows you to call a function inside the same function, then it is called a recursive call of the function.
  • The C programming language supports recursion, i.e., a function to call itself. But while using recursion, programmers need to be careful to define an exit condition from the function, otherwise it will go into an infinite loop.
  • Recursive functions are very useful to solve many mathematical problems, such as calculating the factorial of a number, generating Fibonacci series, etc.

Below is the source code for C Program to check number is divisible by 11 and 9 using recursion which is successfully compiled and run on Windows System to produce desired output as shown below :


SOURCE CODE : :


/* Program that tests whether a number is divisible by 11 and 9 or not */


#include<stdio.h>
int divisibleBy9(long int x);
int divisibleBy11(long int x);

int main( )
{
	long int num;
	printf("Enter the number to be tested : ");
	scanf("%ld", &num);

	if(divisibleBy9(num))
		printf("\nThe number is divisible by 9\n");
	else
		printf("\nThe number is not divisible by 9\n");

	if(divisibleBy11(num))
		printf("\nThe number is divisible by 11\n");
	else
		printf("\nThe number is not divisible by 11\n");

		return 0;

}/*End of main()*/

int divisibleBy9( long int n )
{
	int sumofDigits;
	if(n==9)
		return 1;
	if(n<9)
		return 0;
	sumofDigits=0;
	while(n>0)
	{
		sumofDigits += n%10;
		n/=10;
	}
	divisibleBy9(sumofDigits);
}/*End of divisibleBy9()*/

int divisibleBy11( long int n )
{
	int s1=0, s2=0,diff;

	if(n == 0)
		return 1;
	if(n < 10)
		return 0;

	while(n>0)
	{
		s1 += n%10;
		n /=10;
		s2 += n%10;
		n /= 10;
	}
	diff = s1>s2 ? (s1-s2) : (s2-s1);
	divisibleBy11(diff);
}/*End of divisibleBy11()*/


OUTPUT  : :


***************OUTPUT***************


***************FIRST RUN************

Enter the number to be tested : 6534

The number is divisible by 9

The number is divisible by 11



***************SECOND RUN************

Enter the number to be tested : 657

The number is divisible by 9

The number is not divisible by 11



***************THIRD RUN************

Enter the number to be tested : 742

The number is not divisible by 9

The number is not divisible by 11



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