vfprintf formats output for an I/O stream from a va_list. A variadic wrapper initializes and later releases the argument list, then delegates formatted printing instead of processing each argument itself. section 17.4.2
Delegating a variadic wrapper
A wrapper can use va_start to initialize a va_list, pass that list to vfprintf together with a format, and call va_end afterward. The wrapper therefore avoids manually inspecting argument types or tracking individual values. section 17.4.2
Key constraints:
- A va_list does not provide its own length; the surrounding variadic interface must establish a convention for detecting the end. section 17.4.2
- Passing the va_list to vfprintf leaves argument case analysis and tracking to the C library’s formatted-printing implementation. section 17.4.2
void va_start(va_list ap, ...);
void va_end(va_list ap);
\textit{type} va_arg(va_list ap, \textit{type});
void va_copy(va_list dest, va_list src);
Review the related va_list operations used to prepare and release arguments around a vfprintf call. section 17.4.2
