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C++ Program to Find Sum of First and Last Digit of a Number



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This article is created to provide some programs in C++ to find and print the sum of first and last digit of a given number. The program is created in following ways:

Find Sum of First and Last Digit using while Loop

The question is, write a program in C++ that receives a number from user as input and print the sum of first and last digit of given number as output. Here is its answer:

#include<iostream>

using namespace std;
int main()
{
   int num, temp=0, last, rem, sum=0;
   cout<<"Enter a Number: ";
   cin>>num;
   while(num!=0)
   {
      if(temp==0)
      {
         last = num%10;
         temp++;
      }
      rem = num%10;
      num = num/10;
   }
   sum = rem + last;
   cout<<"\nSum of First ("<<rem<<") and Last ("<<last<<") Digit = "<<sum;
   cout<<endl;
   return 0;
}

The snapshot given below shows the initial output produced by above C++ program on finding the sum of first and last digit of given number:

c++ find sum of first and last digit of number

Now supply the number say 23094 as input and press ENTER key to find and print the sum of first (that is 2) and last (that is 4) digit of this number like shown in the snapshot given below:

find sum of first and last digit c++

In above program, the dry run of following block of code:

   while(num!=0)
   {
      if(temp==0)
      {
         last = num%10;
         temp++;
      }
      rem = num%10;
      num = num/10;
   }

with num=23094, temp=0, sum=0 goes like:

Find Sum of First and Last Digit using for Loop

Since for loop also contains initialize and update statements along with condition checking. Therefore, just place any initialization say temp=0 or sum=0 and the update statement as num = num/10 like shown in the program given below:

#include<iostream>

using namespace std;
int main()
{
   int num, temp, last, rem, sum=0;
   cout<<"Enter a Number: ";
   cin>>num;
   for(temp=0; num!=0; num=num/10)
   {
      if(temp==0)
      {
         last = num%10;
         temp++;
      }
      rem = num%10;
   }
   sum = rem + last;
   cout<<"\nSum of First ("<<rem<<") and Last ("<<last<<") Digit = "<<sum;
   cout<<endl;
   return 0;
}

This program exactly produces same output as of previous program.

Find Sum of First and Last Digit using Function

This is the last program of this article, created using a user defined function named sumfun() that takes the given number as its argument and returns the sum of first and last digit of its argument.

#include<iostream>
using namespace std;

int sumfun(int);
int main()
{
   int num, sum;
   cout<<"Enter a Number: ";
   cin>>num;
   sum = sumfun(num);
   cout<<"\nSum of First and Last Digit = "<<sum;
   cout<<endl;
   return 0;
}
int sumfun(int n)
{
   int t=0, l, r, s=0;
   while(n!=0)
   {
      if(t==0)
      {
         l = n%10;
         t++;
      }
      r = n%10;
      n = n/10;
   }
   s = r + l;
   return s;
}

Here is its sample run with user input 12030:

find sum of first last digit using function c++

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