string/FreeBSD/wcsxfrm.3

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  36 .\"     @(#)strxfrm.3   8.1 (Berkeley) 6/4/93
  37 .\" FreeBSD: src/lib/libc/string/strxfrm.3,v 1.16 2002/09/06 11:24:06 tjr Exp
  38 .\" $FreeBSD: src/lib/libc/string/wcsxfrm.3,v 1.2 2002/12/09 14:04:05 ru Exp $
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  40 .Dd October 4, 2002
  41 .Dt WCSXFRM 3
  42 .Os
  43 .Sh NAME
  44 .Nm wcsxfrm
  45 .Nd transform a wide string under locale
  46 .Sh LIBRARY
  47 .Lb libc
  48 .Sh SYNOPSIS
  49 .In wchar.h
  50 .Ft size_t
  51 .Fn wcsxfrm "wchar_t * restrict dst" "const wchar_t * restrict src" "size_t n"
  52 .Sh DESCRIPTION
  53 The
  54 .Fn wcsxfrm
  55 function transforms a null-terminated wide character string pointed to by
  56 .Fa src
  57 according to the current locale collation order
  58 then copies the transformed string
  59 into
  60 .Fa dst .
  61 No more than
  62 .Fa n
  63 wide characters are copied into
  64 .Fa dst ,
  65 including the terminating null character added.
  66 If
  67 .Fa n
  68 is set to 0
  69 (it helps to determine an actual size needed
  70 for transformation),
  71 .Fa dst
  72 is permitted to be a
  73 .Dv NULL
  74 pointer.
  75 .Pp
  76 Comparing two strings using
  77 .Fn wcscmp
  78 after
  79 .Fn wcsxfrm
  80 is equivalent to comparing
  81 two original strings with
  82 .Fn wcscoll .
  83 .Sh RETURN VALUES
  84 Upon successful completion,
  85 .Fn wcsxfrm
  86 returns the length of the transformed string not including
  87 the terminating null character.
  88 If this value is
  89 .Fa n
  90 or more, the contents of
  91 .Fa dst
  92 are indeterminate.
  93 .Sh SEE ALSO
  94 .Xr setlocale 3 ,
  95 .Xr strxfrm 3 ,
  96 .Xr wcscmp 3 ,
  97 .Xr wcscoll 3
  98 .Sh STANDARDS
  99 The
 100 .Fn wcsxfrm
 101 function
 102 conforms to
 103 .St -isoC-99 .
 104 .Sh BUGS
 105 The current implementation of
 106 .Fn wcsxfrm
 107 only works in single-byte
 108 .Dv LC_CTYPE
 109 locales, and falls back to using
 110 .Fn wcsncpy
 111 in locales with extended character sets.
 112 .Pp
 113 Comparing two strings using
 114 .Fn wcscmp
 115 after
 116 .Fn wcsxfrm
 117 is
 118 .Em not
 119 always equivalent to comparison with
 120 .Fn wcscoll ;
 121 .Fn wcsxfrm
 122 only stores information about primary collation weights into
 123 .Fa dst ,
 124 whereas
 125 .Fn wcscoll
 126 compares characters using both primary and secondary weights.