**Variadic arguments** is the term used to refer to the arguments of a variadic function.

# Variadic functions

A **variadic function** is one that takes a variable number of arguments. A common example is the `printf()` function defined in the `<stdio.h>` header.

The declaration of a variadic function uses ellipses as the last parameter. 

The prototype for the `printf()` function is as follows:

```C
int printf(const char* format, ...);
```

# Accessing variadic arguments

To access variadic arguments, we must include the `<stdarg.h>` header.

We use the following library facilities:

Facilities defined in <stdarg.h>

#include <stdio.h>
#include <stdarg.h>

int variadic_addition (int count,...)
{
  va_list args;
  int i, sum;

  va_start (args, count);         /* Save arguments in list. */

  sum = 0;
  for (i = 0; i < count; i++)
    sum += va_arg (args, int);    /* Get the next argument value. */

  va_end (args);                  /* Stop traversal. */
  return sum;
}


int main(){

  // call 1: 4 arguments
  printf("Sum: %d\n", variadic_addition(3, 10, 20, 30));

  //call 2: 6 arguments
  printf("Sum: %d\n", variadic_addition(5, 10, 20, 30, 40, 50));

  return 0;

}

`variadic_addition()` adds all the variadic arguments and returns the sum.

This function is able to process both calls that were made, each with a different number of arguments.

Facility	Use
va_start	start access to variadic arguments
va_arg	access the next variadic argument
va_copy	makes a copy of the variadic arguments
va_end	end traversal of variadic arguments
va_list	holds information needed by other facilities

What are variadic arguments in C?

Variadic functions

Accessing variadic arguments

Facilities defined in <stdarg.h>

Code