相关疑难解决方法(0)

我偶然发现了一个我最初无法解释的奇怪行为(见ideone):

#include <iostream>
#include <sstream>
#include <string>

int main() {
  std::cout << "Reference     : "
            << (void const*)"some data"
            << "\n";

  std::ostringstream s;
  s << "some data";
  std::cout << "Regular Syntax: " << s.str() << "\n";

  std::ostringstream s2;
  std::cout << "Semi inline   : "
            << static_cast<std::ostringstream&>(s2 << "some data").str()
            << "\n";

  std::cout << "Inline        : "
            << dynamic_cast<std::ostringstream&>(
                 std::ostringstream() << "some data"
               ).str()
            << "\n";
}

给出输出:

Reference     : 0x804a03d
Regular Syntax: some data
Semi inline   : some …