vfprintf

Prints formatted output based on an argument list.

#include  <stdio.h>

int vfprintf  (FILE *file_ptr, const char *format,
              va_list arg);

file_ptr: A pointer to the file to which the output is directed.
format: A pointer to a string containing the format specification. For more information about format and conversion specifications and their corresponding arguments, see Chapter 2.
arg: A list of expressions whose resultant types correspond to the conversion specifications given in the format specifications.

See the vprintf and vsprintf functions in this section.

See Chapter 2 for information on format specifiers.

x	The number of bytes written.
Negative value	Indicates an output error. The function sets errno. For a list of possible errno values set, see fprintf in this section.