Re: Writing unsigned char to std::ostream
David Wilkinson wrote:
Christof Meerwald wrote:
On Sun, 02 Sep 2007 12:37:44 -0400, David Wilkinson wrote:
In my MFC project I have a piece of code like
void XMLHelper::WriteHeader(std::ostream& ostrm)
{
ostrm.put(unsigned char(0xEF)); // 1
ostrm.put(unsigned char(0xBB));
ostrm.put(unsigned char(0xBF));
Why don't you use:
ostrm << '\xef' << '\xbb' << '\xbf';
or even
ostrm << "\xef\xbb\xbf";
Christof:
Because it seems it is not guaranteed to work.
Christof:
My apologies. I missed the crucial distinction between "hexadecimal
constants" and "hexadecimal character constants".
I'm sure the history of this fiasco is that originally I tried
ostrm.put(0xEF);
and got integer truncation warnings. This caused me to do
ostrm.put(unsigned char(0xEF));
A big, BIG, mistake, which caused me to get involved with compound type
name issues and integer conversion issues. What I should have done was
ostrm.put('\xEF');
Nothing wrong with this, I think, but for a text file perhaps operator
<<() would be better, as you suggest.
I always knew that if I was taken out of my ASCII/8 bit char/2's
complement-centric world then things might get ugly, and I was right!
Thanks again. Hexadecimal character constants. Got it now.
--
David Wilkinson
Visual C++ MVP
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