How to load all files from a directory?

Question

Like the title says; how do I load every file in a directory? I'm interested in both c++ and lua.

Edit: For windows I'd be glad for some real working code and especially for lua. I can do with boost::filesystem for c++.

Answer 1

Listing files in a directory is defined by the platform so you would have to use a platform dependent library. This is true of c++ and Lua (which implements only ansi c functionality).

Answer 2

For Lua, you want the module Lua Filesystem.

As observed by Nick, accessing the file system itself (as opposed to individual files) is outside the scope of the C and C++ standards. Since Lua itself is (with the exception of the dynamic loader used to implement require() for C modules) written in standard C, the core language lacks many file system features.

However, it is easy to extend the Lua core since (nearly) any platform that has a file system also supports DLLs or shared libraries. Lua File system is a portable library that adds support for directory iteration, file attribute discovery, and the like.

With lfs, emulating some of the capability of DIR in Lua is essentially as simple as:

require "lfs"
dot = arg[1] or "."
for name in lfs.dir(dot) do
    local fqn = dot.."/"..name
    local attr = lfs.attributes(fqn)
    print(name, attr.mode, os.date("%Y-%m-%d %H:%M",attr.modification), attr.size)
end

Which produces output that looks like:

E:...>t-lfs.lua
.       directory       2009-04-02 13:23        0
..      directory       2009-04-02 13:18        0
foo.txt file    2009-02-23 01:56        0
t-lfs.lua       file    2009-04-02 13:18        241

E:...>

If your copy of Lua came from Lua for Windows, then you already have lfs installed, and the above sample will work out of the box.

Edit: Incidentally, the Lua solution might also be a sensible C or C++ solution. The Lua core is not at all large, provides a dynamic, garbage-collected language, and is easy to interact with from C either as a hosting application or as an extension module. To use lfs from a C application, you would link with the Lua DLL, initialize a Lua state, and get the state to execute the require"lfs" either via luaL_dostring() or by using the C API to retrieve the require() function from the global table, push the string "lfs", and call the Lua function with something like lua_pcall(L,1,1,0), which leaves the lfs table on the top of the Lua stack.

This approach probably makes the most sense if you already had a need for an embedded scripting language, and Lua meets your requirements.

Answer 3

For a C++ solution, have a look at the Boost.Filesystem library.

Answer 4

require "lfs"

function loadall(dir)
  for file in lfs.dir(dir) do
    if string.find(file, ".lua$") then
      dofile(dir .. "/".. file)     
    end
  end
end