Getting ready

The source code we will compile is one of the examples for the filesystem library provided by Boost to interact with the filesystem. This library is conveniently cross-platform and abstracts the differences between operating systems and filesystems into a coherent, high-level API. The following example code (path-info.cpp) will accept a path as an argument and print a report about its components to the screen:

#include <iostream>

#include <boost/filesystem.hpp>

using namespace std;
using namespace boost::filesystem;

const char *say_what(bool b) { return b ? "true" : "false"; }

int main(int argc, char *argv[]) {
  if (argc < 2) {
    cout
        << "Usage: path_info path-element [path-element...]\n"
           "Composes a path via operator/= from one or more path-element arguments\n"
           "Example: path_info foo/bar baz\n"
#ifdef BOOST_POSIX_API
           " would report info about the composed path foo/bar/baz\n";
#else // BOOST_WINDOWS_API
           " would report info about the composed path foo/bar\\baz\n";
#endif
    return 1;
  }

  path p;
  for (; argc > 1; --argc, ++argv)
    p /= argv[1]; // compose path p from the command line arguments

  cout << "\ncomposed path:\n";
  cout << " operator<<()---------: " << p << "\n";
  cout << " make_preferred()-----: " << p.make_preferred() << "\n";

  cout << "\nelements:\n";
  for (auto element : p)
    cout << " " << element << '\n';

  cout << "\nobservers, native format:" << endl;
#ifdef BOOST_POSIX_API
  cout << " native()-------------: " << p.native() << endl;
  cout << " c_str()--------------: " << p.c_str() << endl;
#else // BOOST_WINDOWS_API
  wcout << L" native()-------------: " << p.native() << endl;
  wcout << L" c_str()--------------: " << p.c_str() << endl;
#endif
  cout << " string()-------------: " << p.string() << endl;
  wcout << L" wstring()------------: " << p.wstring() << endl;

  cout << "\nobservers, generic format:\n";
  cout << " generic_string()-----: " << p.generic_string() << endl;
  wcout << L" generic_wstring()----: " << p.generic_wstring() << endl;

  cout << "\ndecomposition:\n";
  cout << " root_name()----------: " << p.root_name() << '\n';
  cout << " root_directory()-----: " << p.root_directory() << '\n';
  cout << " root_path()----------: " << p.root_path() << '\n';
  cout << " relative_path()------: " << p.relative_path() << '\n';
  cout << " parent_path()--------: " << p.parent_path() << '\n';
  cout << " filename()-----------: " << p.filename() << '\n';
  cout << " stem()---------------: " << p.stem() << '\n';
  cout << " extension()----------: " << p.extension() << '\n';

  cout << "\nquery:\n";
  cout << " empty()--------------: " << say_what(p.empty()) << '\n';
  cout << " is_absolute()--------: " << say_what(p.is_absolute()) << 
  '\n';
  cout << " has_root_name()------: " << say_what(p.has_root_name()) << 
  '\n';
  cout << " has_root_directory()-: " << say_what(p.has_root_directory()) << '\n';
  cout << " has_root_path()------: " << say_what(p.has_root_path()) << 
  '\n';
  cout << " has_relative_path()--: " << say_what(p.has_relative_path()) << '\n';
  cout << " has_parent_path()----: " << say_what(p.has_parent_path()) << '\n';
  cout << " has_filename()-------: " << say_what(p.has_filename()) << 
  '\n';
  cout << " has_stem()-----------: " << say_what(p.has_stem()) << '\n';
  cout << " has_extension()------: " << say_what(p.has_extension()) <<  
  '\n';

  return 0;
}