Sophie: libfreetds0-doc-0.82-12.mga1 i586

libfreetds0-doc-0.82-12.mga1.i586.rpm

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>About Unicode, UCS-2, and UTF-8</TITLE
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> User Guide: A Guide to Installing, Configuring, and Running <SPAN
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>FreeTDS</SPAN
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><H1
><A
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>Appendix B. About Unicode, UCS-2, and UTF-8</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="aboutunicode.htm#ASCII"
><ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>: What everyone knows</A
></DT
><DT
><A
HREF="iso8859.htm"
>ISO 8859: What everyone would like to forget</A
></DT
><DT
><A
HREF="unicode.htm"
>Unicode: East meets West</A
></DT
><DT
><A
HREF="unicodegoodbad.htm"
>Unicode's Pluses and Minuses</A
></DT
><DT
><A
HREF="unicodeutf.htm"
>Unicode Transformation Format: UTF-8</A
></DT
><DT
><A
HREF="unicodefreetds.htm"
>Unicode and FreeTDS</A
></DT
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><P
>For better or worse, <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> brings the otherwise innocent programmer into contact with the arcane business of how data are stored and transported.  <SPAN
CLASS="PRODUCTNAME"
>FreeTDS</SPAN
> is a data communications library that of course connects to databases, which are charged with storing information in a way that is neutral to all architectures and languages.  On the surface, that might not seem very complex, even worth discussing.  Under the surface, things are not so simple.  
			</P
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="ASCII"
><ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>: What everyone knows</A
></H1
><P
>The world we are all familiar with, programmingwise, is <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>.  Our email (mostly), our <SPAN
CLASS="QUOTE"
>"text"</SPAN
> files, our web pages (mostly), all use <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> to represent English (or English-like) text. Perhaps because <A
HREF="http://czyborra.com/charsets/iso646.html"
TARGET="_top"
><ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
></A
> <A
NAME="AEN6064"
HREF="#FTN.AEN6064"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
>  was standardized back in 1972 by the ISO, it seems like the <SPAN
CLASS="QUOTE"
>"natural"</SPAN
> way to store information.  But let's look under the hood a little bit, and examine our assumptions.  
			</P
><P
>Our so-called <SPAN
CLASS="QUOTE"
>"text"</SPAN
> files are nothing special, nothing but a little agreement we enter into with our operating system.  The only reason we can <SPAN
CLASS="QUOTE"
>"read"</SPAN
> them with <B
CLASS="COMMAND"
>cat</B
> or <B
CLASS="COMMAND"
>vi</B
> is that the operating system and its tools are in on the agreement.  A file is only a stream of bytes, after all, no more <SPAN
CLASS="QUOTE"
>"text"</SPAN
> than an executable.  The only thing distinguishing a <SPAN
CLASS="QUOTE"
>"text"</SPAN
> file from any other, is our understanding to treat it like one.  We agree that the number 65 will represent the letter <TT
CLASS="LITERAL"
>A</TT
>, 66, <TT
CLASS="LITERAL"
>B</TT
>, and so on, 127 values in all.  See <B
CLASS="COMMAND"
>man ascii</B
> for further details.  
			</P
><P
>The important thing to understand is that the designation of 65 for <TT
CLASS="LITERAL"
>A</TT
> and so on is a choice.  It's an <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>encoding standard</I
></SPAN
>, made necessary by the old simple fact that computers store numbers, not letters.  <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> is so ubiquitous these days that it's hard sometimes to remember there was a time when it was but one of a set of competing encoding standards.  Others you probably have heard of include <ACRONYM
CLASS="ACRONYM"
>EBCDIC</ACRONYM
> and the Baudot systems, but they are by no means the only historical alternatives, nor the only modern ones.  
			</P
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="ASCIICOMPACT"
>The <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> Compact</A
></H2
><P
>UNIX&reg; and unix-like systems bought into <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> big time.  Program code, filenames, string constants (and variables), configuration files, everything but everything is encoded in <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>.  Practically every utility, command, and library assumes the <SPAN
CLASS="QUOTE"
>"text"</SPAN
> data will be <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>. At the dawn of the 21<SUP
>st</SUP
> century, there is widespread recognition that <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> will no longer suffice, but the art of upgrading all the computers and computer programmers is, well, an unfinished work.  
			</P
></DIV
></DIV
></DIV
><H3
CLASS="FOOTNOTES"
>Notes</H3
><TABLE
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><TD
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><A
NAME="FTN.AEN6064"
HREF="aboutunicode.htm#AEN6064"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>czyborra.com is offline at the time of this writing (December 2003).  It contained good information, so it's still included here, in case it comes back to life.  </P
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