C Exercises: Sum of a variable number of integers

C Variadic function: Exercise-1 with Solution

Write a C program to find the sum of a variable number of integers passed as arguments to a function using variadic functions.

Sample Solution:

C Code:

#include <stdio.h>

#include <stdarg.h>

int sum_nums(int ctr, ...) {
  int sum_nums_all = 0;
  va_list args;
  va_start(args, ctr);
  for (int i = 0; i < ctr; i++) {
    int n = va_arg(args, int);
    sum_nums_all += n;
  }
  va_end(args);
  return sum_nums_all;
}
int main() {
  int s1 = sum_nums(3, 1, 2, 3); // returns 6
  int s2 = sum_nums(5, 1, 2, 3, 4, 5); // returns 15
  int s3 = sum_nums(3, -1, -2, -3); // returns -6
  printf("s1 = %d, s2 = %d, s3 = %d", s1, s2, s3);
  return 0;
}

Sample Output:

s1 = 6, s2 = 15, s3 = -6  

Explanation:

In the above program, the sum_nums() function takes two arguments, the number of integers to sum up and a variable number of arguments. It initializes a 'va_list' object args with the 'va_start' macro, and then iterates over the variable argument list using the 'va_arg' macro to retrieve each argument as an int. Finally, it cleans up the va_list object using the 'va_end' macro.

In the main function, we call the sum function thrice with different sets of integers, and print the results.

Flowchart:

C Programming Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: C Variadic function Exercises Home
Next: Product of a variable number of integers.