In C programming, the stdarg.h header file provides a set of functions and macros for working with functions that take a variable number of arguments. One of the most important macros in this header file is va_end(), which cleans up a va_list object when you're done using it.

The va_end() macro takes one argument:

void va_end(va_list ap);

The argument, ap, is a va_list object that was previously initialized using va_start().

The va_end() macro cleans up any resources that were allocated for the va_list object ap, and makes it available for reuse. It is important to call va_end() on a va_list object when you're done using it, to avoid memory leaks or other issues.

Here's an example of how to use va_end() to clean up a va_list object:

#include <stdarg.h>

int sum(int num_args, ...)
{
    va_list ap;
    int arg, total = 0;

    va_start(ap, num_args);

    for (int i = 0; i < num_args; i++) {
        arg = va_arg(ap, int);
        total += arg;
    }

    va_end(ap);

    return total;
}

In the above example, the va_end() macro is called after the for loop that retrieves the variable arguments from the va_list object. This ensures that any resources associated with the va_list object are properly cleaned up before the sum() function returns.