<p>Consider this code. One thread repeatedly prints the number 100 in decimal to std::cout. Another thread repeatedly prints the number 0x100 in hex (which will output as '100') to std::cout.</p><p>You might reasonably expect that the output will simply be '100' over and over and over.</p><p>Unfortunately, the calls to operator<< can get interleaved so you end up with crosstalk of the format specifiers:</p>
