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Re: copyright symbol

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Andrew Poulos wrote:

> I have an MS SQL Server database with a copyright symbol in a field of
> data type varchar(80). When this is read by JScript in a classic ASP and
> then displayed in the page the symbol displays as a black diamond with a
> question mark in it.

That is a possible rendering of U+FFFD REPLACEMENT CHARACTER.  It is used 
here because the code sequence leading to the character in the database (A9) 
is not a proper UTF-8 code sequence (A9 is reserved as continuation byte).

<https://en.wikipedia.org/wiki/ISO-8859-1#Codepage_layout>
 
> If I change the page's charset from
>    <meta charset="UTF-8">
> to
>    <meta charset="iso-8859-1">
> the symbol correctly displays as a copyright symbol.
> 
> Why does changing the charset "fix" the display of the symbol?
> 
> I'd rather keep the charset as UTF but I'm at a loss as to what's going
> on.

The term “charset” is historical and misleading.  This “meta” element 
specifies the character *encoding* of the resource unless there is an HTTP 
“Content-Type” header field value that takes precedence.  This client-side 
change has an effect, so you are not serving a “Content-Type” header field 
value with a ”charset” parameter; your server-side code is incomplete or in 
error.

<http://www.w3.org/TR/2014/CR-html5-20140204/infrastructure.html#fetching-resources>

UTF-8 is the Unicode encoding that uses 8 bits per code unit.  A Unicode 
character, precisely its code point, can be encoded with up to four such 
code units.

<http://unicode.org/faq/>

> Do I need to change the data type?

No.

> Do I need to encode the symbol before it goes into the database?

No, but it would be a good idea.

> Do I need to unescape/decode the value from the database?

Yes, you need to *re*code string values if the database uses a different 
character encoding than the document resource you are generating.

This problem has very little to do with ECMAScript implementations.

Next time, do research.

<http://www.joelonsoftware.com/articles/unicode.html>

-- 
PointedEars
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Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
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copyright symbol Andrew Poulos <ap_prog@hotmail.com> - 2014-06-04 14:36 +1000
  Re: copyright symbol "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2014-06-04 08:51 +0300
    Re: copyright symbol "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-04 10:37 +0200
  Re: copyright symbol Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-04 11:06 +0200
    Re: copyright symbol Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-06-04 14:34 +0200
      Re: copyright symbol "Jukka K. Korpela" <jkorpela@cs.tut.fi> - 2014-06-04 15:41 +0300
    Re: copyright symbol Andrew Poulos <ap_prog@hotmail.com> - 2014-06-05 10:28 +1000
      Re: copyright symbol "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2014-06-05 09:12 +0200
  Re: copyright symbol Denis McMahon <denismfmcmahon@gmail.com> - 2014-06-04 11:21 +0000

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