Welcome Programmer: Armstrong Program in C++

Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits is equal to the number itself. Some Armstrong numbers is 0, 1, 153, 370, 371, 407, 1634 etc.

For example:
Three Digits Armstrong number is 153, 1 ^ 3 + 5 ^ 3 + 3 ^ 3 = 153
Four Digits Armstrong number is 1634, 1 ^ 4 + 6 ^ 4 + 3 ^ 4 + 4 ^ 4 + = 1634

Let's try to understand why 153 is an Armstrong number.

Example

153 = (1*1*1)+(5*5*5)+(3*3*3)  
where:  
(1*1*1)=1  
(5*5*5)=125  
(3*3*3)=27  
So:  
1+125+27=153

Let's try to understand why 371 is an Armstrong number.

Example

371 = (3*3*3)+(7*7*7)+(1*1*1)  
where:  
(3*3*3)=27  
(7*7*7)=343  
(1*1*1)=1  
So:  
27+343+1=371

Let's try to understand why 1634 is an Armstrong number.

Example

1634 = (1*1*1*1)+(6*6*6*6)+(3*3*3*3)+(4*4*4*4)
where:  
(1*1*1*1) = 1  
(6*6*6*6) = 1296  
(3*3*3*3) = 81 
(4*4*4*4) = 256
So:  
1+1296+81+256= 1634

3 Digits Armstrong Program in C++

Armstrong Program in C++

#include<iostream.h>
#include<conio.h>

void main()
{
int arm=0,a,b,c,d,no; 
clrscr();
cout<<"Enter any num: ";
 cin>>no;
d=no;
while(no>0)
{
a=no%10;
no=no/10;
arm=arm+a*a*a;
}
if(arm==d)
{
cout<<"Armstrong";
}
else
{
cout<<"not Armstrong";
}
getch();
}

Output

Enter any number: 23
not Armstrong

Any number of Digits Armstrong Program in C++

Example

#include<iostream.h>
#include<conio.h>
void main()
{
 int num;
 int f,rem,sum=0,temp,a=0;
 clrscr();
 cout<<"Enter any number: ";
 cin>>num;
 temp=num;
 while(temp != 0)
 {
 temp=temp/10;
 a=a+1;
 }
 f=num;
 while(f!=0)
 {
 rem=f%10;
 sum = sum + power(rem,a);
 f=f/10;
 }

 if( sum == num )
 cout<<"\n Armstrong number ";
 else
 cout<<"\n Not a Armstrong number";
 getch();
}

int power(int c, int d)
{
    int pow=1;
    int i=1;
    while(i<=d)
    {
      pow=pow*c;
      i++;
     }
     return pow;
}

Output

Enter any number: 153
Armstrong number

Explanation of Program

temp=num;
 while(temp != 0)
  {
  temp=temp/10;
  a=a+1;
  }

This code is for calculate the number of digits in given/entered number by user. above temp variable assign the enter number by user (temp=num). Every time temp divided by 10 and result store in temp if temp become zero loop will be terminated