Skip to main content

Find Sum of Digits of a Number in C

Objective: Your are given a number and you have to find the sum of its digits. Like 1234 so its digits sum 1+2+3+4=10.

Programming technique : This problem  can be solved using the fact that modulus operator (%) gives the last digit when divided by 10. So we successively Divide it , till all numbers are exhausted.
so The program runs like this >>
1234%10 gives last digit. that is 4. (we save it ) then divide the number by 10 to reduce it.
1234/10=123. and repeat the process till the number becomes 0.
First run : 1234%10 gives 4, 1234/10=123.
Second run: 123%10 gives 3 , 123/10=12.
Third Run :12%10 gives 2 , 12/10=1
Fourth run: 1%10 gives 1, 1/10=0 (we stop here).
pretty easy stuff.

Code :-
#include<stdio.h>

int main()
{
    int k;
    printf("\n enter any number=");
    scanf("%d",&k);
    printf("\n sum of digit=%d",sumdigit(k));
          return(0);
}

int sumdigit(int x)
{
    int sum=0;// will save sum
    int r=0; // for remainder
    while(x>0)
    {
        r=x%10;//get remainder
        sum+=r;//sum it
        x=x/10;    //reduce number
    }
    return(sum);
}

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 ; ...

Program to find nth Prime number in C

Objective: To print any Prime number in C.  This task may sound easy but is a very good exercise to help optimize CPU intensive programs. Finding Prime number is a very CPU hogging task and it becomes even more dreaded as the number starts to grow. Lets say we want to find 30001th prime. how will we find it?? Here is the program. Programming logic : The easiest method is to check if the given number N is divisible by any number from 2 to N-1. But it may be noted that we don't need to go beyond the number that is square root of N.  why?? lets have a look. Say we are testing number 49 for prime number. Our objective is to find any number that may divide it. so we start from 2,3,4 etc. As soon as we cross 7 there will be no number that will divide 49, if there was we have got it earlier since it will be smaller then 7.  Get it? another example 64 : 2x32 4x16 8x8 16x4 32x2 as you can see when we pass number 8 we don't need to test as the number that will come ,...