C++ Cookbook

10.12. Reading the Contents of a Directory

Problem

You need to read the contents of a directory, most likely to do something to each file or subdirectory that’s in it.

Solution

To write something portable, use the Boost Filesystem library’s classes and functions. It provides a number of handy utilities for manipulating files, such as a portable path representation, directory iterators, and numerous functions for renaming, deleting, and copying files, and so on. Example 10-19 demonstrates how to use a few of these facilities.

Example 10-19. Reading a directory

#include <iostream>
#include <boost/filesystem/operations.hpp>
#include <boost/filesystem/fstream.hpp>

using namespace boost::filesystem;

int main(int argc, char** argv) {

   if (argc < 2) {
      std::cerr << "Usage: " << argv[0] << " [dir name]\n";
      return(EXIT_FAILURE);
   }

   path fullPath =    // Create the full, absolute path name
     system_complete(path(argv[1], native));

   if (!exists(fullPath)) {
      std::cerr << "Error: the directory " << fullPath.string()
                << " does not exist.\n";
      return(EXIT_FAILURE);
   }

   if (!is_directory(fullPath)) {
      std::cout << fullPath.string() << " is not a directory!\n";
      return(EXIT_SUCCESS);
   }

   directory_iterator end;
   for (directory_iterator it(fullPath);
        it != end; ++it) {               // Iterate through each
                                         // element in the dir,
      std::cout << it->leaf();           // almost as you would
      if (is_directory(*it))             // an STL container
         std::cout << " (dir)";
      std::cout << '\n';
   }

   return(EXIT_SUCCESS);
}

Discussion

Like creating or deleting directories ...