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rockgtr (10)
I am making a program to check if a number is a Armstrong number or not. A Armstrong number is a number in which the sum of the cube of the digits is equal to the number itself ( In 153 1*1*1+5*5*5+3*3*3=153). Please help. Thanks in advance.

#include<iostream.h>
#include<process.h>
void main()
{
int a,b,c,d,e,f;
cout<<"\t\tAMSTRONG NUMBER(0-999)";
cout<<"\n\nEnter the number=";
cin>>a;
b=a%10;
f=a/10;
c=a%10;
f=f/10;
d=c%10;
e=b*b*b+c*c*c+d*d*d;
if(a==e)
cout<<"\nThis is a Amrstrong number.";
else
cout<<"\nThis is not a Armstrong number.";
}
Last edited on
Aceix (1118)
I guess you can use a string stream, so extracting the digits would be easier.

Aceix.
giblit (3750)
main should return int, it should be iostream.h also why do you have process included?

As far as your problem what exactly are these supposed to be? 
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b=a%10; //right digit
f=a/10; //left 2 digits
c=a%10; //right digit
f=f/10; //arbitrary number divided by 10
d=c%10 //right digit mod 10 = right digit still


Here is how I would do it 
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#include <iostream>

int main()
{
    int Armstrong = 0;
    std::cout << "Please enter a number: ";
    std::cin >> Armstrong;
    
    int right = Armstrong % 10;
    int middle = Armstrong / 10 % 10;
    int left = Armstrong / 100;
    int sum = right * right * right + middle * middle * middle + left * left * left;
    
    std::cout << "The number " << Armstrong << " is " << (sum == Armstrong ? "" : "not") << " an Armstrong number." << std::endl;
    
    return 0;
}

Please enter a number: 152
The number 152 is not an Armstrong number.

...

Please enter a number: 153
The number 153 is  an Armstrong number.


*was missing third - for output
Last edited on
dhayden (5798)
Even if you fix your code, it will only work for up to three digits. I seem to recall that the largest Armstrong numbers are less than 1,000, but lets pretend we don't know that. So why not write a function that computes the sum of the cube of the digits:

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int sumCubeDigits(int num)
{
    int result = 0;
    while (num) {
        int digit = num %10;    // get least significant digit
        result += digit*digit*digit;
        num %= 10;                 // shift num down one digit. e.g. 123 -> 12
    }
    return result;
}


Now a number is an Armstrong number if num == sumCubeDigits(num)
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