distrib/share/tcl/help/tcl/intl/encoding

   1 NAME
   2        encoding - Manipulate encodings
   3
   4 SYNOPSIS
   5        encoding option ?arg arg ...?
   6
   7
   8 INTRODUCTION
   9        Strings  in Tcl are encoded using 16-bit Unicode characters.  Different
  10        operating system interfaces or applications  may  generate  strings  in
  11        other  encodings  such  as  Shift-JIS.   The  encoding command helps to
  12        bridge the gap between Unicode and these other formats.
  13
  14 DESCRIPTION
  15        Performs one of  several  encoding  related  operations,  depending  on
  16        option.  The legal options are:
  17
  18        encoding convertfrom ?encoding? data
  19               Convert  data to Unicode from the specified encoding.  The char-
  20               acters in data are treated as binary data where the lower 8-bits
  21               of  each  character  is  taken  as a single byte.  The resulting
  22               sequence of bytes is treated as a string in the specified encod-
  23               ing.   If encoding is not specified, the current system encoding
  24               is used.
  25
  26        encoding convertto ?encoding? string
  27               Convert string from Unicode  to  the  specified  encoding.   The
  28               result  is  a  sequence  of  bytes that represents the converted
  29               string.  Each byte is stored in the lower 8-bits  of  a  Unicode
  30               character.   If  encoding  is  not specified, the current system
  31               encoding is used.
  32
  33        encoding names
  34               Returns a list containing the names of all of the encodings that
  35               are currently available.
  36
  37        encoding system ?encoding?
  38               Set the system encoding to encoding. If encoding is omitted then
  39               the command returns the current  system  encoding.   The  system
  40               encoding is used whenever Tcl passes strings to system calls.
  41
  42 EXAMPLE
  43        It  is  common  practice to write script files using a text editor that
  44        produces output in the euc-jp  encoding,  which  represents  the  ASCII
  45        characters  as  singe bytes and Japanese characters as two bytes.  This
  46        makes it easy to embed literal strings  that  correspond  to  non-ASCII
  47        characters  by  simply typing the strings in place in the script.  How-
  48        ever, because the source command always reads files using  the  current
  49        system  encoding,  Tcl  will  only source such files correctly when the
  50        encoding used to write the file is the same.  This tends not to be true
  51        in  an  internationalized  setting.   For  example,  if such a file was
  52        sourced in North America (where the ISO8859-1 is normally  used),  each
  53        byte  in the file would be treated as a separate character that maps to
  54        the 00 page in Unicode.  The resulting Tcl strings will not contain the
  55        expected Japanese characters.  Instead, they will contain a sequence of
  56        Latin-1 characters that correspond to the bytes of the original string.
  57        The encoding command can be used to convert this string to the expected
  58        Japanese Unicode characters.  For example,
  59               set s [encoding convertfrom euc-jp "\xA4\xCF"]
  60        would return the Unicode string "\u306F", which is the Hiragana  letter
  61        HA.
  62
  63
  64 SEE ALSO
  65        Tcl_GetEncoding(3)
  66
  67
  68 KEYWORDS