Is there any API in c++ for getting the size of a specified folder?
If not, how can I get the total size of a folder including all subfolders and files?
The file system functions are integral part of each operative system, written mostly in C and assembler, not C++, each C++ library implementation for this are in one way or another a wrapper of this functions. Taking on count the effort and if you will not use your implementation in different OS, maybe is a good idea to use this functions directly and save some overhead and time.
Best regards.