C++ Boost Filesystem Library(Part II): Example Programs

Continuing from where I had left in my earlier post containing the basics of the C++ Boost Filesystem Library, below are some example programs that make use of some common facilities available in the Boost Filesystem Library. I assume that all the code snippets shown in this post are properly nested within the main() function apart from including the following things:
[cpp]
#include
#include
#include
namespace bfs=boost::filesystem;
[/cpp]

1. Simple program to demonstrate the use of file creation and removal operations:
[cpp]
std::cout<<"Enter your choice:\n";
std::cout<<"1. Create folder\n2. Rename File\n3. Remove File\n4. Copy File\n";
char ch;
std::cin>>ch;
std::string name, new_name;
switch(ch)
{
case ’1′:
std::cout<<"Enter folder name:";
std::cin>>name;
bfs::create_directory(bfs::path(name));
break;
case ’2′:
std::cout<<"Enter file name:";
std::cin>>name;
std::cout<<"Enter new name:";
std::cin>>new_name;
bfs::rename(name, new_name);
break;
case ’3′:
std::cout<<"Enter file name:";
std::cin>>name;
bfs::remove(bfs::path(name));
break;
case ’4′:
std::cout<<"Enter file name:";
std::cin>>name;
std::cout<<"Enter new name:";
std::cin>>new_name;
bfs::copy_file(name, new_name);
break;
}
std::cout<<"Operation finished."< }
[/cpp]
Pay attention to the following four Boost Filesystem functions used:
[cpp]
bfs::create_directory(bfs::path(name));
bfs::rename(name, new_name);
bfs::remove(bfs::path(name));
bfs::copy_file(name, new_name);
[/cpp]
They all do what their function names suggest. Like its always the case with the simple example programs, no error checking is done here ;)

2. Removing all the files from a directory:
[cpp]
std::cout<<"Enter the name of the folder to empty:";
std::string name;
std::cin>>name;
bfs::remove_all(bfs::path(name));
std::cout<<"Operation completed."< [/cpp]

The other examples needs an introduction to the directory_iterator class which is used to iterate over the contents of a directory. A simple usage looks like this:
[cpp]
bfs::path p(“folder”);
bfs::directory_iterator dir_iter(p), dir_end;
for(;dir_iter != dir_end; ++dir_iter)
{
std::cout<<(*dir_iter).leaf();
}
[/cpp]
A directory_iterator object can be created by passing it a name of a directory. Applying the prefix increment operator(++) to it makes it point to the next file in the directory. Applying the indirection operator(*) returns the file currently being pointed to, as a ‘path’ object. We call the leaf() method on the returned ‘path’ object to print the file name. Using ‘dir_iter->leaf()’ instead of ‘(*dir_iter).leaf()’ has the same effect.

Using a ‘directory_iter’ object, we can create a function similar to the ‘remove_all()’ function that we used in Example 2.
3. Removing all the files from a directory by iteration:
[cpp]
std::cout<<"Enter the name of the folder to empty:";
std::string name;
std::cin>>name;
bfs::path p(name);
if(!bfs::exists(p) || !bfs::is_directory(p))
{
std::cout<<"Invalid input."< exit(-1);
}
bfs::directory_iterator dir_iter(p), dir_end;
for(;dir_iter != dir_end; ++dir_iter)
{
std::cout<<"Removing file: "<leaf();
bfs::remove(*dir_iter);
}
std::cout<<"Operation Completed."< [/cpp]
Simple error checking is done on the input before calling the remove()function on all the files present in the specified folder. Will follow up with more examples using the Boost Filesystem Library.