当我在我的g++ --version终端上运行Cloud9时,我得到了g++ (GCC) 4.4.7 20120313 (Red Hat 4.4.7-3)。这是一个相当老的版本--足够老了,当我尝试使用C++11库特性(如std::unordered_set )时,我得到:"This file requires compiler and library support for the upcoming ISO C++ standard, C++0x. This support is currently experimental, and must be enabled with the