Why is void f(…) not allowed in C?

Question

Why doesn\'t C allow a function with variable length argument list such as:

void f(...)
{
    // do something...
}

Answer 1

The ... allows for no arguments, ie: for int printf(const char *format, ...); the statement

printf("foobar\n");

is valid.

If you don't mandate at least 1 parameter (which should be used to check for more parameters), there is no way for the function to "know" how it was called.

All these statements would be valid

f();
f(1, 2, 3, 4, 5);
f("foobar\n");
f(qsort);