vdprintf()

Write output to a file associated with a file descriptor (varargs)

Synopsis:

#include <stdio.h>
#include <stdarg.h>

int vdprintf( int filedes,
              const char* format,
              va_list arg );

filedes: A file descriptor that's associated with the file where you want to send the output.
format: A string that specifies the format of the output. The formatting string determines what additional arguments you need to provide. For more information, see printf().
arg: A variable-argument list of the additional arguments, which you must have initialized with the va_start() macro.

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

The vdprintf() function writes output to the file associated with the file descriptor filedes, under control of the format specifier.

The vdprintf() function is a “varargs” version of dprintf().

The number of characters written, or a negative value if an output error occurred (errno is set).