stdio/FreeBSD/fgetwln.3

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  28 .\"     @(#)fgetln.3    8.3 (Berkeley) 4/19/94
  29 .\" $FreeBSD: src/lib/libc/stdio/fgetwln.3,v 1.3 2007/01/09 00:28:06 imp Exp $
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  31 .Dd July 16, 2004
  32 .Dt FGETWLN 3
  33 .Os
  34 .Sh NAME
  35 .Nm fgetwln ,
  36 .Nm fgetwln_l
  37 .Nd get a line of wide characters from a stream
  38 .Sh LIBRARY
  39 .Lb libc
  40 .Sh SYNOPSIS
  41 .In stdio.h
  42 .In wchar.h
  43 .Ft wchar_t *
  44 .Fn fgetwln "FILE * restrict stream" "size_t * restrict len"
  45 .In xlocale.h
  46 .Ft wchar_t *
  47 .Fn fgetwln_l "FILE * restrict stream" "size_t * restrict len" "locale_t loc"
  48 .Sh DESCRIPTION
  49 The
  50 .Fn fgetwln
  51 function
  52 returns a pointer to the next line from the stream referenced by
  53 .Fa stream .
  54 This line is
  55 .Em not
  56 a standard wide character string as it does not end with a terminating
  57 null wide character.
  58 The length of the line, including the final newline,
  59 is stored in the memory location to which
  60 .Fa len
  61 points.
  62 (Note, however, that if the line is the last
  63 in a file that does not end in a newline,
  64 the returned text will not contain a newline.)
  65 .Pp
  66 While the
  67 .Fn fgetwln
  68 function uses the current locale, the
  69 .Fn fgetwln_l
  70 function may be passed a locale directly. See
  71 .Xr xlocale 3
  72 for more information.
  73 .Sh RETURN VALUES
  74 Upon successful completion a pointer is returned;
  75 this pointer becomes invalid after the next
  76 .Tn I/O
  77 operation on
  78 .Fa stream
  79 (whether successful or not)
  80 or as soon as the stream is closed.
  81 Otherwise,
  82 .Dv NULL
  83 is returned.
  84 The
  85 .Fn fgetwln
  86 function
  87 does not distinguish between end-of-file and error; the routines
  88 .Xr feof 3
  89 and
  90 .Xr ferror 3
  91 must be used
  92 to determine which occurred.
  93 If an error occurs, the global variable
  94 .Va errno
  95 is set to indicate the error.
  96 The end-of-file condition is remembered, even on a terminal, and all
  97 subsequent attempts to read will return
  98 .Dv NULL
  99 until the condition is
 100 cleared with
 101 .Xr clearerr 3 .
 102 .Pp
 103 The text to which the returned pointer points may be modified,
 104 provided that no changes are made beyond the returned size.
 105 These changes are lost as soon as the pointer becomes invalid.
 106 .Sh ERRORS
 107 .Bl -tag -width Er
 108 .It Bq Er EBADF
 109 The argument
 110 .Fa stream
 111 is not a stream open for reading.
 112 .El
 113 .Pp
 114 The
 115 .Fn fgetwln
 116 function
 117 may also fail and set
 118 .Va errno
 119 for any of the errors specified for the routines
 120 .Xr mbrtowc 3 ,
 121 .Xr realloc 3 ,
 122 or
 123 .Xr read 2 .
 124 .Sh SEE ALSO
 125 .Xr ferror 3 ,
 126 .Xr fgetln 3 ,
 127 .Xr fgetws 3 ,
 128 .Xr fopen 3 ,
 129 .Xr xlocale 3