C++ program to check Armstrong number
In this chapter of C++ program tutorial out task is:

Write a c++ program to check whether a number is armstrong number or not
C++ program to check Armstrong number
Given below is the c++ program to check armstrong number or not.
/* Program Name : To check whether a number is Armstrong or not
Program Author : Sayantan Bose
*/
#include<iostream>
//math.h header file is used for the sqrt function
#include <math.h>
using namespace std;
//This function will return the sum of the digits powered to the length of the inputed number.
int arms (int num)
{
int r,sum=0,num1=num,c=0;
while(num!=0)
{
c++;
num=num/10;
}
while(num1!=0)
{
r=num1%10;
num1=num1/10;
sum=sum+pow(r,c);
}
return sum;
}
// This is the main function
int main() {
int num,sum=0,new_num;
cout<<"Enter any number to check Armstrong:";
cin>>num;
new_num=num;
sum=arms(num);
if(sum==new_num)
cout<<sum<<" is an Armstrong number";
else
cout<<sum<<" is not an Armstrong number";
return 0;
}
OUTPUT
Enter the number to check Armstrong:
153
153 is an Armstrong number
Or
Enter the number to check Armstrong:
53
53 is not an Armstrong number
EXPLANATION :
In the above c++ program to check if a number is Armstrong or not:

A number is said to be Armstrong if and only if the sum of its digits powered to the length of the number is equal to the number itself.

For example: 153 is an Armstrong number. Because 153 can be written as the sum of 1^{3}+5^{3}+3^{3}, where 3 is the length of the provided number 153.

In the method arms, we are calculating the sum of each digit powered to the length of the inputed number. And then the sum is returned to the main method.

In the main method the sum is then compared with the original number provided as input.

If both of them turn out to be equal the number is an Armstrong number else it isn't.
āYou can see the above code execution and output in codeblocks IDE:
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About the Author
Sayantan Bose
 š Iām currently working on DS Algo skills
 š± Iām currently learning web develeopement
 šÆ Iām looking to collaborate with Oppia
 š« Reach me at https://www.linkedin.com/in/sayantanbose14134a1a6/
 š Pronouns: his/him
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Published Date :
Dec 07,2020