Re: [C++] Encoding: XSCryptCryptoBase64::encode()

[Berin Lautenbach]

Rude words.  I think that was mentioned by someone else some time back.
Thankyou for picking up the reason.  I tend to equate bit-wise 
operations (unspecified ordering) with logical operations (defined 
ordering) and so get caught in this trap.

Thanks!  I will fix in CVS this weekend.
Cheers,
        Berin

Milan Tomic wrote:
Berin,
I've found very interesting problem with encoding. Take a look at this 
line of the code from XSCryptCryptoBase64::encode():

t = ((m_inputBuffer[i++] << 4) & 0x30) | (m_inputBuffer[i] >> 4);
The problem is that order of execution (left to right or right to left) 
is not defined for "|" operator in C++ language and is left to compiler 
to decide. There are cases where first is being executed left side of 
operator "|" and there are cases where first is executed right side and 
then left side. Because of operator ++ in expression i++, results are 
different and encoding fails. I've noticed this behaviour (right to left 
order) using Multithreaded (/MT) runtime, but when I use Multitreaded 
DLL (/MD) runtime order is left to right (using VC7.1 compiler). The 
best way to avoid this is to break this line into (at least) two lines 
and avoid ++ operator side effect.

Best regards,
Milan