stdio/fread.3

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  36 .\"     @(#)fread.3     8.2 (Berkeley) 3/8/94
  37 .\" $FreeBSD: src/lib/libc/stdio/fread.3,v 1.9 2002/10/12 16:13:37 mike Exp $
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  39 .Dd March 8, 1994
  40 .Dt FREAD 3
  41 .Os
  42 .Sh NAME
  43 .Nm fread ,
  44 .Nm fwrite
  45 .Nd binary stream input/output
  46 .Sh LIBRARY
  47 .Lb libc
  48 .Sh SYNOPSIS
  49 .In stdio.h
  50 .Ft size_t
  51 .Fn fread "void *restrict ptr" "size_t size" "size_t nitems" \
  52     "FILE *restrict stream"
  53 .Ft size_t
  54 .Fn fwrite "const void *restrict ptr" "size_t size" "size_t nitems" \
  55     "FILE *restrict stream"
  56 .Sh DESCRIPTION
  57 The function
  58 .Fn fread
  59 reads
  60 .Fa nitems
  61 objects, each
  62 .Fa size
  63 bytes long, from the stream pointed to by
  64 .Fa stream ,
  65 storing them at the location given by
  66 .Fa ptr .
  67 .Pp
  68 The function
  69 .Fn fwrite
  70 writes
  71 .Fa nitems
  72 objects, each
  73 .Fa size
  74 bytes long, to the stream pointed to by
  75 .Fa stream ,
  76 obtaining them from the location given by
  77 .Fa ptr .
  78 .Sh RETURN VALUES
  79 The functions
  80 .Fn fread
  81 and
  82 .Fn fwrite
  83 advance the file position indicator for the stream
  84 by the number of bytes read or written.
  85 They return the number of objects read or written.
  86 If an error occurs, or the end-of-file is reached,
  87 the return value is a short object count (or zero).
  88 .Pp
  89 The function
  90 .Fn fread
  91 does not distinguish between end-of-file and error; callers
  92 must use
  93 .Xr feof 3
  94 and
  95 .Xr ferror 3
  96 to determine which occurred.
  97 The function
  98 .Fn fwrite
  99 returns a value less than
 100 .Fa nitems
 101 only if a write error has occurred.
 102 .Sh SEE ALSO
 103 .Xr read 2 ,
 104 .Xr write 2
 105 .Sh STANDARDS
 106 The functions
 107 .Fn fread
 108 and
 109 .Fn fwrite
 110 conform to
 111 .St -isoC .