usr/src/lib/libc/stdio/fread.3

.\" Copyright (c) 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
.\" %sccs.include.redist.man%
.\"
.\"     @(#)fread.3     6.5 (Berkeley) %G%
.\"
.Dd
.Dt FREAD 3
.Os
.Sh NAME
.Nm fread ,
.Nm fwrite
.Nd binary stream input/output
.Sh SYNOPSIS
.Fd #include <stdio.h>
.Ft int
.Fn fread "void *ptr" "size_t size" "size_t nmemb" "FILE *stream"
.Ft int
.Fn fwrite "void *ptr" "size_t size" "size_t nmemb" "FILE *stream"
.Sh DESCRIPTION
The function
.Fn fread
reads
.Fa nmemb
elements of data, each
.Xr size
bytes long, from the stream pointed to by
.Fa stream ,
storing them at the location given by
.Fa ptr .
.Pp
The function
.Fn fwrite
writes
.Fa nmemb
elements of data, each
.Fa size
bytes long, to the stream pointed to by
.Fa stream ,
obtaining them from the location given by
.Fa ptr .
.Sh RETURN VALUES
The functions
.Fn fread
and
.Fn fwrite
advance the file position indicator for the stream
by the number of characters successfully read or written and return
that number.
If an error occurs, or the end-of-file is reached,
the return value is a short character count (or zero).
.Pp
The function
.Fn fread
does not distinguish between end-of-file and error, and callers
must use
.Xr feof 3
and
.Xr ferror 3
to determine which occurred.
.Sh SEE ALSO
.Xr read 2 ,
.Xr write 2
.Sh STANDARDS
The functions
.Fn fread
and
.Fn fwrite
conform to
.St -ansiC .