Reordering includes to have a common order in them: groups separated with an empty line, files in one group in alphabetical order, main groups in order as defined below, subgroups by directories in alphabetical order. Main grouping order: (1) the corresponding declaring header for a .cpp file, (2) local headers under lib with relative path, (3) public headers from include with project-relative path, (3) 3rd party headers, (4) system headers, (5) standard headers.