Re: Writing unsigned char to std::ostream

From:
"David Webber" <dave@musical-dot-demon-dot-co.uk>
Newsgroups:
microsoft.public.vc.language
Date:
Sun, 2 Sep 2007 18:00:01 +0100
Message-ID:
<#Sx4SLY7HHA.1204@TK2MSFTNGP03.phx.gbl>
"David Wilkinson" <no-reply@effisols.com> wrote in message
news:OLC3W%23X7HHA.4660@TK2MSFTNGP02.phx.gbl...

...
  ostrm.put(unsigned char(0xEF)); // 1
...
It fails due to the use of unsigned char as a type in this context. Both
of the following compile correctly (not sure about running):

ostrm.put(unsigned(0xEF)); // 2
ostrm.put((unsigned char)0xEF); // 3


My 2d-worth: I'd have used the last, or maybe even

ostrm.put( (unsigned char)(0xEF) );

just because it looks like stretching things to destruction to have a
function-style cast with an apparent "function name" containing a space.

1. Is this a parsing bug in g++/Comeau?


If it is, it's not one which surprises me!

 > 2. Do you think the following is correct and portable?

void XMLHelper::WriteHeader(std::ostream& ostrm)
{
  ostrm << static_cast<unsigned char>(0xEFU);
  ostrm << static_cast<unsigned char>(0xBBU);
  ostrm << static_cast<unsigned char>(0xBFU);
  ostrm << "<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n";
}


Not sure - but it looks ugly with all those <<<< :-)

My instinct for clarity and security would be

ostrm.put( (unsigned char)(0xEF) );

Alternatively, how about

typedef unsigned char __uint8;

ostrm.put( __uint8(0xEF) );

:-)

Dave
--
David Webber
Author of 'Mozart the Music Processor'
http://www.mozart.co.uk
For discussion/support see
http://www.mozart.co.uk/mzusers/mailinglist.htm

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