fflush

Defined in header <stdio.h>
int fflush( FILE* stream );

For output streams (and for update streams on which the last operation was output), writes any unwritten data from the stream's buffer to the associated output device.

For input streams (and for update streams on which the last operation was input), the behavior is undefined.

If stream is a null pointer, all open output streams are flushed, including the ones manipulated within library packages or otherwise not directly accessible to the program.

Parameters

stream

-

the file stream to write out

Return value

Returns zero on success. Otherwise EOF is returned and the error indicator of the file stream is set.

Notes

POSIX extends the specification of fflush ungetc or ungetwc

Microsoft also extends the specification of fflush by defining its effects on an input stream: in Visual Studio 2013 and prior, it discarded the input buffer, in Visual Studio 2015 and newer, it has no effect, buffers are retained

References

See also

fopenfopen_s (C11)	opens a file (function)
fclose	closes a file (function)
C++ documentation for fflush