xref: /freebsd/lib/libc/stdio/fflush.3 (revision 41466b50c1d5bfd1cf6adaae547a579a75d7c04e)
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36.\"     @(#)fflush.3	8.1 (Berkeley) 6/4/93
37.\" $FreeBSD$
38.\"
39.Dd June 4, 1993
40.Dt FFLUSH 3
41.Os
42.Sh NAME
43.Nm fflush ,
44.Nm fpurge
45.Nd flush a stream
46.Sh LIBRARY
47.Lb libc
48.Sh SYNOPSIS
49.In stdio.h
50.Ft int
51.Fn fflush "FILE *stream"
52.Ft int
53.Fn fpurge "FILE *stream"
54.Sh DESCRIPTION
55The function
56.Fn fflush
57forces a write of all buffered data for the given output or update
58.Fa stream
59via the stream's underlying write function.
60The open status of the stream is unaffected.
61.Pp
62If the
63.Fa stream
64argument is
65.Dv NULL ,
66.Fn fflush
67flushes
68.Em all
69open output streams.
70.Pp
71The function
72.Fn fpurge
73erases any input or output buffered in the given
74.Fa stream .
75For output streams this discards any unwritten output.
76For input streams this discards any input read from the underlying object
77but not yet obtained via
78.Xr getc 3 ;
79this includes any text pushed back via
80.Xr ungetc .
81.Sh RETURN VALUES
82Upon successful completion 0 is returned.
83Otherwise,
84.Dv EOF
85is returned and the global variable
86.Va errno
87is set to indicate the error.
88.Sh ERRORS
89.Bl -tag -width Er
90.It Bq Er EBADF
91.Fa Stream
92is not an open stream, or, in the case of
93.Fn fflush ,
94not a stream open for writing.
95.El
96.Pp
97The function
98.Fn fflush
99may also fail and set
100.Va errno
101for any of the errors specified for the routine
102.Xr write 2 .
103.Sh SEE ALSO
104.Xr write 2 ,
105.Xr fclose 3 ,
106.Xr fopen 3 ,
107.Xr setbuf 3
108.Sh STANDARDS
109The
110.Fn fflush
111function
112conforms to
113.St -isoC .
114