C++文件读写ifstream, ofstream

https://cplusplus.com/doc/tutorial/files/

• ofstream: Stream class to write on files，如写文件时需要附加而不是覆盖原文件内容，可

  std::ofstream outfile;
  outfile.open("test.txt", std::ios_base::app); // append instead of overwrite

• ifstream: Stream class to read from files
• fstream: Stream class to both read and write from/to files.