Author: mysqlpp
Date: Thu Sep 29 13:22:45 2011
New Revision: 2696
URL: http://svn.gna.org/viewcvs/mysqlpp?rev=2696&view=rev
Log:
Added UTF-16 and Windows 7 info.
Modified:
trunk/doc/userman/unicode.dbx
Modified: trunk/doc/userman/unicode.dbx
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/doc/userman/unicode.dbx?rev=2696&r1=2695&r2=2696&view=diff
==============================================================================
--- trunk/doc/userman/unicode.dbx (original)
+++ trunk/doc/userman/unicode.dbx Thu Sep 29 13:22:45 2011
@@ -30,10 +30,13 @@
characters using only 7-bit ASCII.</para>
<para>Unicode solves this problem. It encodes every character used
- for writing in the world, using up to 4 bytes per character. The
+ for writing in the world, using up to 4 bytes per character. The
subset covering the most economically valuable cases takes two bytes
- per character, so most Unicode-aware programs deal in 2-byte
- characters, for efficiency.</para>
+ per character, so many Unicode-aware programs only support this
+ subset, storing characters as 2-byte values, rather than use 4-byte
+ characters so as to cover all possible cases, however rare. This
+ subset of Unicode is called the Basic Multilingual Plane, or
+ BMP.</para>
<para>Unfortunately, Unicode was invented about two decades
too late for Unix and C. Those decades of legacy created an
@@ -97,12 +100,20 @@
<title>Unicode on Windows</title>
<para>Each Windows API function that takes a string actually comes
- in two versions. One version supports only 1-byte “ANSI”
- characters (a superset of ASCII), so they end in 'A'. Windows also
- supports the 2-byte subset of Unicode called <ulink
- url="http://en.wikipedia.org/wiki/UCS-2";>UCS-2</ulink>. Some call
- these “wide” characters, so the other set of functions
- end in 'W'. The <function><ulink
+ in two versions. One version supports only 1-byte
+ “ANSI” characters (a superset of ASCII), so they end
+ in 'A'. Windows also supports the 2-byte subset of Unicode called
+ <ulink
+ url="http://en.wikipedia.org/wiki/UCS-2";>UCS-2</ulink><footnote><para>Since
+ Windows XP, Windows actually uses the <ulink
+ url="http://en.wikipedia.org/wiki/UTF-16";>UTF-16</ulink> encoding,
+ not UCS-2. This means that if you use characters beyond the 16-bit
+ “BMP” range, they get encoded as 4-byte characters. But
+ again, since the most economically valuable subset of Unicode is the
+ BMP, many programs ignore this distinction and treat modern Windows
+ as supporting 2-byte characters.</para></footnote>. Some call these
+ “wide” characters, so the other set of functions end
+ in 'W'. The <function><ulink
url="http://msdn.microsoft.com/library/en-us/winui/winui/windowsuserinterface/windowing/dialogboxes/dialogboxreference/dialogboxfunctions/messagebox.asp";>MessageBox</ulink>()</function>
API, for instance, is actually a macro, not a real function. If you
define the <symbol>UNICODE</symbol> macro when building your
@@ -168,11 +179,12 @@
routines.</para>
<para>All of this assumes you’re using Windows NT or one of
- its direct descendants: Windows 2000, Windows XP, Windows Vista, or
- any “Server” variant of Windows. Windows 95 and its
- descendants (98, ME, and CE) do not support UCS-2. They still have
- the 'W' APIs for compatibility, but they just smash the data down to
- 8-bit and call the 'A' version for you.</para>
+ its direct descendants: Windows 2000, Windows XP, Windows Vista,
+ Windows 7, or any “Server” variant of Windows.
+ Windows 95 and its descendants (98, ME, and CE) do not support
+ Unicode. They still have the 'W' APIs for compatibility, but they
+ just smash the data down to 8-bit and call the 'A' version for
+ you.</para>
</sect2>
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