A.2.2 How Variadic Functions are Defined and Used
Defining and using a variadic function involves three steps:
- Define the function as variadic, using an ellipsis
(‘…’) in the argument list, and using special macros to
access the variable arguments.  See Receiving the Argument Values.
 - Declare the function as variadic, using a prototype with an
ellipsis (‘…’), in all the files which call it.
See Syntax for Variable Arguments.
 - Call the function by writing the fixed arguments followed by the
additional variable arguments.  See Calling Variadic Functions.