用VS不报错，但是用Devc++一直报错

Question

file.open(filename, ifstream::in | ifstream::app);

85 51 C:\Users\86186\Documents\tencent files\2120733640\filerecv\mobilefile\stumangement(1).cpp [Error] no matching function for call to 'std::basic_fstream::open(std::string&, std::_Ios_Openmode)'

file.open(filename, ifstream::out );

100 37 C:\Users\86186\Documents\tencent files\2120733640\filerecv\mobilefile\stumangement(1).cpp [Error] no matching function for call to 'std::basic_fstream::open(std::string&, const openmode&)'

Answer 1

filename.c_str()