Skip to main content

Find Armstrong Number in C

Finding Armstrong number is again a great exercise for students The exercise involves clever use of modulus operator to extract the digits and then using those digits to perform calculations.

Armstrong Number : These are the special numbers which is equal to the sum of the cube of their own digits.
like 153. since 153= 13+53+33=1+125+27=153 cool isn't it. So how can you find them? Here is the logic.
Logic: use modulus operator to get the last digit of the number. so 153%10=3 (last digit). cube this number, 3*3*3=27, then save it to a variable. again now reduce the number 153. 153/10=15 (see the last digit will be removed :) ). repeat the process till this number becomes 0.
Code:

#include<stdio.h>

int armstrong(int x)
{
    //copy x to k
    int k=x;
    
    //start extracting its digit, 
    // cube the digit and start saving it
    // we will use sum to save the total.
    int sum=0;
    int r=0;
    //r will be used for remainder
    while(k>0)
    {
        r=k%10;
        //now cude the remainder and add it to sum
        sum+=r*r*r;
        //reduce k by 10
        k=k/10;    
    }
    if(x==sum)
    {
        return(1);
    }
    else
    {
        return(0);
    }
}

int main()
{
    int k=0;
    //n will be used how far we want to calculate
    int n;
    printf("\n Enter a number=");
    scanf("%d",&n);
    for(k=0;k<=n;k++)
    {
        if(armstrong(k))
        {
            printf("\n Armstring number=%d",k);
        }
    }
    
}
Labels:

Popular posts from this blog

Overloading Unary Operator in C++

In this Example I will demonstrate overloading a unary operator. The overloading is done in similar way as we did for binary operator. In this example I will be using a Vector Class. The operator we are going to over load is the unary "~" (tilde) operator. although you can use any unary overloadable operator. Method: In this example the overloaded operator will be the part of the class i.e. the over loaded definition will be a member function. (As we know overloading can be done using non member functions too). So the unary operator will not have any arguments in it. We will overload ~ operator so that it will reflect the vector so that its z component becomes x component and vice versa. So input vector will be 2i+3j+5k and its output vector will be 5i+3j+2k. although you can do anything you like. Code: # include < iostream > using namespace std ; class vector { int x , y , z ;      public : vector ( ) { x = y = z = 0 ; ...
Read more

constructor overloading in c++

Constructor play an important part in c++. They can initialize the values of a given object to some known values. This is important as constructor will be able to set some values in objects which otherwise may have some garbage values. Most uninitialized value in objects are main cause of the bugs. But the concept of constructor can allow us to do just anything beside initializing values. Constructor are always called when an object is created. This property of constructor is very useful in situation when you need to perform some task as soon as an object is created. So constructor is a special function that gets called automatically when an object is created. This function can like any other function do anything (like initializing values). Overloading Constructor : This process is very similar to the overloading of simple functions. Since constructor are also function , they can be overloaded like any other functions. This allows user to create many constructor, which can help u...
Read more