C Program to Check Armstrong Number

In this example, we take on input from user and check entered number is Armstrong or not.

What is Armstrong Number?

In number theory, a Armstrong number in a given number base b is a number that is the sum of its own digits each raised to the power of the number of digits.

For example, using a simple number 153 and the decimal system, we see there are 3 digits in it. If we do a simple mathematical operation of raising each of its digits to the power of 3, and then obtain total, we get 153. That is 1 to the power of 3 5 to the power of 3 3 to the power of three is 1 125 27 153. This can also be represented as 1^3 5^3 3^3=153. The number 153 is an example of the Armstrong number which also has a unique property that one can use any number system.

C Program to Check Whether a Number is Armstrong or Not Using Loop

	
#include<stdio.h>  
int main()    
{    
    int n,r,sum=0,temp;    
    printf("Enter the number ::");    
    scanf("%d",&n);    
    
    temp=n;    
    
    while(n>0)    
    {    
        r=n%10;    
        sum=sum+(r*r*r);    
        n=n/10;    
    }    
    if(temp==sum)    
        printf("Number is Armstrong  Number ");    
    else    
        printf("Number is not Armstrong Number");    
    return 0;  
}   
	

Output :

	
//Output : 1
Enter the number ::153
Number is Armstrong  Number
//Output : 2
Enter the number ::122
Number is not Armstrong Number
	

C Program to Check Whether a Number is Armstrong or Not Using User Define Function

	
#include<stdio.h>

int isArmstrong(int number) 
{
    int lastDigit = 0;
    int power = 0;
    int sum = 0;

    int n = number;

    while(n!=0) {

        lastDigit = n % 10;

        power = lastDigit*lastDigit*lastDigit;

        sum += power;

        n /= 10;
    }

    if(sum == number) return 0;
    else return 1;
}

int main()
{
    int number;

    printf("Enter number: ");
    scanf("%d",&number);

    if(isArmstrong(number) == 0)
    printf("%d is an Armstrong number.\n", number);
    else
    printf("%d is not an Armstrong number.", number);

    return 0;
}
	

Output :

	
Enter number: 8526
8526 is not an Armstrong number.
	

C Program to Check Whether a Number is Armstrong or Not Using Recursion

	
#include<stdio.h>
#include<math.h>
int is_armstrong(int num)
{
    if(num>0)
    return (pow(num%10,3) +is_armstrong(num/10));
}
int main()
{
    int num;
    printf("Enter a number:");
    scanf("%d",&num);
    if(is_armstrong(num)==num)
        printf("It is an Armstrong Number");
    else
        printf("It is not an Armstrong Number");
}
	

Output :

	
Enter a number:370
It is an Armstrong Number
	

C Program to Display Armstrong Numbers Between Two Intervals

	
#include<stdio.h>  
int main()    
{    
    int start,end,r,sum=0,i,n;    
    printf("Enter the starting point ::");    
    scanf("%d",&start);     
    printf("Enter the starting point ::");    
    scanf("%d",&
    end);    
    
    printf("Armstrong numbers between %d and %d are ::",start,end);
    for(i=start;i<=end;i++)
    {
        n=i;   
        sum = 0;
        while(n>0)    
        {    
            r=n%10;    
            sum=sum+(r*r*r);    
            n=n/10;    
        }    
        
        if(i==sum)
        {
            printf(" %d ",i);
        }
    }
    return 0;          
}   
	

Output :

	
Enter the starting point ::50
Enter the starting point ::500
Armstrong numbers between 50 and 500 are :: 153  370  371  407