ios_base
想问一下ios_base和ios关系，使用ios::out 和ios_base::out 貌似效果一样

[解决办法]

C/C++ code

Bitmask type to represent stream error state flags.See alsoios::rdstate     Get error state flags (public member function)ios::setstate     Set error state flag (public member function)ios::good     Check if the state of the stream is good for i/o operations. (public member function)ios::bad     Check if badbit is set (public member function)ios::fail     Check if either failbit or badbit is set (public member function )ios::eof     Check if eofbit is set (public member function)