Writes out any buffered information for the specified file.

    Format

      #include  <stdio.h>

      int fflush  (FILE *file_ptr);

1 - Argument

 file_ptr

    A file pointer. If this argument is a NULL pointer, all buffers
    associated with all currently open files are flushed.

2 - Description

    The output files are normally buffered only if they are not
    directed to a terminal, except for stderr, which is not buffered
    by default.

    The fflush function flushes the Compaq C RTL buffers. However,
    RMS has its own buffers. The fflush function does not guarantee
    that the file will be written to disk. (See the description of
    fsync for a way to flush buffers to disk.)

    If the file pointed to by file_ptr was opened in record mode
    and if there is unwritten data in the buffer, then fflush always
    generates a record.

3 - Return Values

    0                  Indicates that the operation is successful.
    EOF                Indicates that the buffered data cannot be
                       written to the file, or that the file control
                       block is not associated with an output file.