trusty (3) encoding.3tcl.gz

NAME

       encoding - Manipulate encodings

SYNOPSIS

       encoding option ?arg arg ...?
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INTRODUCTION

       Strings  in  Tcl  are  encoded using 16-bit Unicode characters.  Different operating system interfaces or
       applications may generate strings in other encodings such as Shift-JIS.  The encoding  command  helps  to
       bridge the gap between Unicode and these other formats.

DESCRIPTION

       Performs one of several encoding related operations, depending on option.  The legal options are:

       encoding convertfrom ?encoding? data
              Convert data to Unicode from the specified encoding.  The characters in data are treated as binary
              data where the lower 8-bits of each character is taken as a single byte.  The  resulting  sequence
              of  bytes  is  treated  as  a string in the specified encoding.  If encoding is not specified, the
              current system encoding is used.

       encoding convertto ?encoding? string
              Convert string from Unicode to the specified encoding.  The result is a  sequence  of  bytes  that
              represents  the converted string.  Each byte is stored in the lower 8-bits of a Unicode character.
              If encoding is not specified, the current system encoding is used.

       encoding names
              Returns a list containing the names of all of the encodings that are currently available.

       encoding system ?encoding?
              Set the system encoding to encoding. If encoding is omitted then the command returns  the  current
              system encoding.  The system encoding is used whenever Tcl passes strings to system calls.

EXAMPLE

       It  is  common  practice  to  write  script  files using a text editor that produces output in the euc-jp
       encoding, which represents the ASCII characters as singe bytes and  Japanese  characters  as  two  bytes.
       This  makes it easy to embed literal strings that correspond to non-ASCII characters by simply typing the
       strings in place in the script.  However, because the source command always reads files using the current
       system  encoding,  Tcl  will only source such files correctly when the encoding used to write the file is
       the same.  This tends not to be true in an internationalized setting.  For example, if such  a  file  was
       sourced  in  North America (where the ISO8859-1 is normally used), each byte in the file would be treated
       as a separate character that maps to the 00 page in Unicode.  The resulting Tcl strings will not  contain
       the  expected  Japanese  characters.   Instead,  they  will contain a sequence of Latin-1 characters that
       correspond to the bytes of the original string.  The encoding command can be used to convert this  string
       to the expected Japanese Unicode characters.  For example,
              set s [encoding convertfrom euc-jp "\xA4\xCF"]
       would return the Unicode string "\u306F", which is the Hiragana letter HA.

SEE ALSO

       Tcl_GetEncoding(3tcl)

KEYWORDS

       encoding