Hi Freddie,

I reported this strange behaviour on the boost.devel list some time ago. Unfortunately, I did not get an answer.
Several people I know ran into this trap and it would be very helpful if a char is converted to int in case of %d formatter.

A cast to int should help:
std::cout << (fmt % (int)port) << std::endl;

Best regards,
Philipp

On 11/3/06, Wu Yinghui, Freddie <yhwu@volumeinteractions.com> wrote:
Hi all,

I'm using Boost CVS version in the release branch. But according to the
change log, it seems that this problem shall exist in Boost 1.33 too.

I have the following code snippet, which doesn't produce the desired output:

typedef unsigned char qquint8;
qquint8 port = 1;
boost::format fmt("Trying to probe COM%1$d:...");
std::cout << (fmt % port) << std::endl;

The output will was:
        Trying to probe COM^A:...
but what I want should be:
        Trying to probe COM1:...

I understand that the underlying stream might have treated port as a
character, thus output it as a character. But from Boost.Format's
documentation, this doesn't seem obvious to me, since it always refers
this as "printf-like" format string.

So my question is: Is this considered a bug (thus, shall be fixed), or
is it just considered a special case (thus, shall be explicitly
documented under the "Differences of behaviour vs printf" section)?

Cheers,

Freddie

--
Wu Yinghui, Freddie
Research & Development
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