stdio/FreeBSD/fread.3

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  32 .\"     @(#)fread.3     8.2 (Berkeley) 3/8/94
  33 .\" $FreeBSD: src/lib/libc/stdio/fread.3,v 1.10 2007/01/09 00:28:06 imp Exp $
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  35 .Dd March 8, 1994
  36 .Dt FREAD 3
  37 .Os
  38 .Sh NAME
  39 .Nm fread ,
  40 .Nm fwrite
  41 .Nd binary stream input/output
  42 .Sh LIBRARY
  43 .Lb libc
  44 .Sh SYNOPSIS
  45 .In stdio.h
  46 .Ft size_t
  47 .Fn fread "void *restrict ptr" "size_t size" "size_t nitems" \
  48     "FILE *restrict stream"
  49 .Ft size_t
  50 .Fn fwrite "const void *restrict ptr" "size_t size" "size_t nitems" \
  51     "FILE *restrict stream"
  52 .Sh DESCRIPTION
  53 The function
  54 .Fn fread
  55 reads
  56 .Fa nitems
  57 objects, each
  58 .Fa size
  59 bytes long, from the stream pointed to by
  60 .Fa stream ,
  61 storing them at the location given by
  62 .Fa ptr .
  63 .Pp
  64 The function
  65 .Fn fwrite
  66 writes
  67 .Fa nitems
  68 objects, each
  69 .Fa size
  70 bytes long, to the stream pointed to by
  71 .Fa stream ,
  72 obtaining them from the location given by
  73 .Fa ptr .
  74 .Sh RETURN VALUES
  75 The functions
  76 .Fn fread
  77 and
  78 .Fn fwrite
  79 advance the file position indicator for the stream
  80 by the number of bytes read or written.
  81 They return the number of objects read or written.
  82 If an error occurs, or the end-of-file is reached,
  83 the return value is a short object count (or zero).
  84 .Pp
  85 The function
  86 .Fn fread
  87 does not distinguish between end-of-file and error; callers
  88 must use
  89 .Xr feof 3
  90 and
  91 .Xr ferror 3
  92 to determine which occurred.
  93 The function
  94 .Fn fwrite
  95 returns a value less than
  96 .Fa nitems
  97 only if a write error has occurred.
  98 .Sh SEE ALSO
  99 .Xr read 2 ,
 100 .Xr write 2
 101 .Sh STANDARDS
 102 The functions
 103 .Fn fread
 104 and
 105 .Fn fwrite
 106 conform to
 107 .St -isoC .