Passing variable arguments to another function that accepts a variable argument list

Question

So I have 2 functions that both have similar arguments

void example(int a, int b, ...);
void exampleB(int b, ...);

Now example calls exampleB, but how can I pass along the variables in the variable argument list without modifying exampleB (as this is already used elsewhere too).

Answer 1

You can't do it directly; you have to create a function that takes a va_list:

#include <stdarg.h>

static void exampleV(int b, va_list args);

void exampleA(int a, int b, ...)    // Renamed for consistency
{
    va_list args;
    do_something(a);                // Use argument a somehow
    va_start(args, b);
    exampleV(b, args);
    va_end(args);
}

void exampleB(int b, ...)
{
    va_list args;
    va_start(args, b);
    exampleV(b, args);
    va_end(args);
}

static void exampleV(int b, va_list args)
{
    ...whatever you planned to have exampleB do...
    ...except it calls neither va_start nor va_end...
}