100 lines
3.5 KiB
Plaintext
100 lines
3.5 KiB
Plaintext
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'\" Copyright (c) 1998 Scriptics Corporation.
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'\"
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'\" See the file "license.terms" for information on usage and redistribution
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'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\"
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.TH encoding n "8.1" Tcl "Tcl Built-In Commands"
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.so man.macros
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.BS
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.SH NAME
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encoding \- Manipulate encodings
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.SH SYNOPSIS
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\fBencoding \fIoption\fR ?\fIarg arg ...\fR?
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.BE
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.SH INTRODUCTION
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.PP
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Strings in Tcl are logically a sequence of 16-bit Unicode characters.
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These strings are represented in memory as a sequence of bytes that
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may be in one of several encodings: modified UTF\-8 (which uses 1 to 3
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bytes per character), 16-bit
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.QW Unicode
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(which uses 2 bytes per character, with an endianness that is
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dependent on the host architecture), and binary (which uses a single
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byte per character but only handles a restricted range of characters).
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Tcl does not guarantee to always use the same encoding for the same
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string.
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.PP
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Different operating system interfaces or applications may generate
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strings in other encodings such as Shift\-JIS. The \fBencoding\fR
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command helps to bridge the gap between Unicode and these other
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formats.
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.SH DESCRIPTION
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.PP
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Performs one of several encoding related operations, depending on
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\fIoption\fR. The legal \fIoption\fRs are:
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.TP
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\fBencoding convertfrom\fR ?\fIencoding\fR? \fIdata\fR
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.
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Convert \fIdata\fR to Unicode from the specified \fIencoding\fR. The
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characters in \fIdata\fR are treated as binary data where the lower
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8-bits of each character is taken as a single byte. The resulting
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sequence of bytes is treated as a string in the specified
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\fIencoding\fR. If \fIencoding\fR is not specified, the current
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system encoding is used.
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.TP
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\fBencoding convertto\fR ?\fIencoding\fR? \fIstring\fR
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.
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Convert \fIstring\fR from Unicode to the specified \fIencoding\fR.
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The result is a sequence of bytes that represents the converted
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string. Each byte is stored in the lower 8-bits of a Unicode
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character (indeed, the resulting string is a binary string as far as
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Tcl is concerned, at least initially). If \fIencoding\fR is not
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specified, the current system encoding is used.
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.TP
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\fBencoding dirs\fR ?\fIdirectoryList\fR?
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.
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Tcl can load encoding data files from the file system that describe
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additional encodings for it to work with. This command sets the search
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path for \fB*.enc\fR encoding data files to the list of directories
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\fIdirectoryList\fR. If \fIdirectoryList\fR is omitted then the
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command returns the current list of directories that make up the
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search path. It is an error for \fIdirectoryList\fR to not be a valid
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list. If, when a search for an encoding data file is happening, an
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element in \fIdirectoryList\fR does not refer to a readable,
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searchable directory, that element is ignored.
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.TP
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\fBencoding names\fR
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.
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Returns a list containing the names of all of the encodings that are
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currently available.
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The encodings
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.QW utf-8
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and
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.QW iso8859-1
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are guaranteed to be present in the list.
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.TP
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\fBencoding system\fR ?\fIencoding\fR?
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.
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Set the system encoding to \fIencoding\fR. If \fIencoding\fR is
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omitted then the command returns the current system encoding. The
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system encoding is used whenever Tcl passes strings to system calls.
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.SH EXAMPLE
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.PP
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The following example converts a byte sequence in Japanese euc-jp encoding to a TCL string:
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.PP
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.CS
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set s [\fBencoding convertfrom\fR euc-jp "\exA4\exCF"]
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.CE
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.PP
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The result is the unicode codepoint:
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.QW "\eu306F" ,
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which is the Hiragana letter HA.
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.SH "SEE ALSO"
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Tcl_GetEncoding(3)
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.SH KEYWORDS
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encoding, unicode
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.\" Local Variables:
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.\" mode: nroff
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.\" End:
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