C Program to Compute the Sum of Digits in a given Integer

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This is a C program to compute the sum of digits in a given integer.

Problem Description

This program computes the sum of digits in a given integer.

Problem Solution

1. Take the integer as input.
2. Divide the input integer by 10, obtain its remainder and quotient.
3. Increment the new variable with the remainder got at step 2.
4. Repeat the step 2 & 3 with the quotient obtained until the qoutient becomes zero.
5. Print the output and exit.

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Program/Source Code

Here is source code of the C program to compute the sum of digits in a given integer. The C program is successfully compiled and run on a Linux system. The program output is also shown below.

  1. /*
  2.  * C program to accept an integer & find the sum of its digits
  3.  */
  4. #include <stdio.h>
  5.  
  6. void main()
  7. {
  8.     long num, temp, digit, sum = 0;
  9.  
  10.     printf("Enter the number \n");
  11.     scanf("%ld", &num);
  12.     temp = num;
  13.     while (num > 0)
  14.     {
  15.         digit = num % 10;
  16.         sum  = sum + digit;
  17.         num /= 10;
  18.     }
  19.     printf("Given number = %ld\n", temp);
  20.     printf("Sum of the digits %ld = %ld\n", temp, sum);
  21. }
Program Explanation

1. Take an integer as a input and store it in the variable num.
2. Initialize the variable sum to zero.
3. Divide the input integer by 10 and obtain its remainder & quotient.
4. Store the remainder in the variable digit.
5. Increment the variable sum with variable digit.
6. Store the quotient into the variable num.
7. Repeat the steps 3,4,5,6 with the new num.
8. Do step 7 until the quotient becomes zero.
9. Print the variable sum as output and exit.

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Runtime Test Cases
Enter the number
300
Given number = 300
Sum of the digits 300 = 3
 
 
Enter the number
16789
Given number = 16789
Sum of the digits 16789 = 31

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Here’s the list of Best Reference Books in C Programming, Data-Structures and Algorithms>

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If you wish to look at other example programs on Simple C Programs, go to Simple C Programs. If you wish to look at programming examples on all topics of C, go to C Programming Examples.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn