Problem:fflush(3) on different platforms

gvim

As we known that fflush(3) is a standard C library function. So it should be has the same behavior on any platforms which support standard ansi C library.

But when I wrote fflush(stdin);

Windows will discard all things stored in the system's standard input buffer. So when I issue getchar(3) next fflush(3), I could get correct character I wish.

FreeBSD, contrasted with windows, has not the effect like windows. It just flush output to the FILE instead of discard output buffer. Hence fflush(stdin) take no effect. Therefor, another function named fpurge(3) is provided by FreeBSD. But this function is not the standard C library function. Some thing like above, when I getchar(3) next fflush(3), I cann't get thing I want.

Why? Is there any different between windows and BSD to implement fflush(3)?

Any advice will be appreciated. Thanx
GVIM

win_hate

fflush should not be use in stdin, if you do that, the resoult is undefined.

原帖由 "ISO/IEC 9899:1999(E)" 发表：

7.19.5.2 The fflush function
Synopsis
1 #include <stdio.h>;
int fflush(FILE *stream);

Description
2 If stream points to an output stream or an update stream in which the most recent
operation was not input, the fflush function causes any unwritten data for that stream
to be delivered to the host environment to be written to the file; otherwise, the behavior is
undefined.
3 If stream is a null pointer, the fflush function performs this flushing action on all
streams for which the behavior is defined above.
Returns
4 The fflush function sets the error indicator for the stream and returns EOF if a write
error occurs, otherwise it returns zero.
Forward references: the fopen function (7.19.5.3).

gvim

hammm, I got it, thank you