Vinill80s

#include<iostream>
#include<filesystem>
#include<string>

using namespace std;
namespace fs = filesystem;

auto listFilesRecursively = [](auto const& dir, string const& mask = {}){
  if(!fs::is_directory(dir))
  {
    cerr << dir << " is not dir";
    throw "is not dir!";
  }
  
  for(auto const& file : fs::recursive_directory_iterator(dir))
  {
    if(fs::is_regular_file(file))
    {
      if(mask.empty() || file.path().extension().string() == mask)
      {
        // Здесь твоя функция вывода инфы
        cout << file.path().string() << " #size: " << file.file_size() << "\n";
      }
    }
    else if(fs::is_directory(file))
    {
      cout << "\n****** dir ****** [" << file.path().string() << "]\n";
    }
    else
    {
      cout << "\n***** other... ******[" << file.path().filename().string() << "]\n";
    }
  }
};

int main()
{
  const string start_dir = R"(C:\Program Files)";
  try
  {
    listFilesRecursively(start_dir, ".dll");
  }
  catch(exception& e)
  {
    cerr << e.what();
  }
}