Return a list of file names under a specific directory.
This function only works under Windows.
Example 1
vector<wstring> file_name_w = search_file_w(L"*.bmp");
Example 2
vector<wstring> file_name = search_file_w(L"images/*.bmp");
Example 3
vector<string> file_name = search_file("*.bmp");
Example 4
vector<string> file_name = search_file("images/*.bmp");