C++를 사용하여 파일 확장자를 얻는 방법은 무엇입니까?

#include <iostream>
#include <string>

std::string get_file_extension(const std::string& filename) {
  auto last_dot = filename.find_last_of('.');
  if (last_dot == std::string::npos) {
    return "";  // 没有扩展名
  }
  return filename.substr(last_dot + 1);
}

int main() {
  std::string filename = "example.txt";
  std::cout << "File extension: " << get_file_extension(filename) << std::endl;
  return 0;
}

#include <boost/filesystem.hpp>

std::string get_file_extension(const std::string& filename) {
  boost::filesystem::path path(filename);
  return path.extension().string();
}

int main() {
  std::string filename = "example.txt";
  std::cout << "File extension: " << get_file_extension(filename) << std::endl;
  return 0;
}