CPSC 120 Demonstrate how to use the filesystem library and functions to find files and rename them.

cpsc120_rename_jpeg.cc

// Gist https://gist.github.com/f6a5ebf19ad736a3bdcf28be34b84cc4

// To try out this program, you don't need to have a folder full of JPEG images.
// Do the following from from the command line to create some sample data to
// demonstrate how this program works.
// $ mkdir sample_data
// $ cd sample_data
// $ touch blue.jpeg red.jpeg yellow.jpeg orange.jpeg green.jpeg purple.jpeg
// $ cd ..
// $ clang++ -std=c++17 cpsc120_rename_jpeg.cc
// $ ./a.out sample_data
// $ ls sample_data

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

// Given path_string, find the last occurance of base and return the substring
// from the start to the base. For example, given Basename("foo.jpg", ".jpg")
// the function shall return "foo".
std::string Basename(const std::string& path_string, const std::string& base) {
  return path_string.substr(0,
                            path_string.find_last_of(base) - base.size() + 1);
}

// Given a path_string, return true if the path_string ends with ext, else
// false.
bool HasExtension(const std::string& path_string, const std::string& ext) {
  return path_string.substr(path_string.size() - ext.size()) == ext;
}

int main(int argc, char const* argv[]) {
  std::vector<std::string> args{argv, argv + argc};
  if (args.size() < 2) {
    std::cout << "Please provide a path to a directory.\n";
    return 1;
  }
  std::filesystem::path input_directory{args.at(1)};

  if (!std::filesystem::is_directory(input_directory)) {
    std::cout << input_directory << " is not a directory.\n";
    std::cout << "Please provide a path to a directory.\n";
    return 1;
  }
  std::vector<std::string> jpeg_file_list;
  std::string wrong_extension{".jpeg"};
  std::string correct_extension{".jpg"};
  for (const auto& fs_item :
       std::filesystem::directory_iterator(input_directory)) {
    if (fs_item.is_regular_file() and
        HasExtension(fs_item.path().string(), wrong_extension)) {
      std::string base_file_name =
          Basename(fs_item.path().string(), wrong_extension);
      std::filesystem::path renamed_file_path{base_file_name +
                                              correct_extension};
      std::cout << "Renaming " << fs_item.path().string() << " to "
                << renamed_file_path.string() << "\n";
      std::filesystem::rename(fs_item, renamed_file_path);
    }
  }
  return 0;
}