Prints formatted output based on an argument list.

    Format

      #include  <stdio.h>

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

1 - Arguments

 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 the "Understanding Input and
    Output" chapter of the HP C RTL Reference Manual.

 ap

    A list of expressions whose resultant types correspond to the
    conversion specifications given in the format specifications.

2 - Description

    See also vprintf and vsprintf.

3 - Return Values

    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.