How to Create Directories Recursively with Win32

As I just found out, the CreateDirectory function on Win32 can only create one directory at a time. If one, for example, specifies C:\Users\All Users\FirstNew\SecondNew as the directory to create, and both FirstNew and SecondNew do not exist, then CreateDirectory() fails.

That’s less than ideal for some cases. Recently, for example, I wanted my game to create the C:\Users\<Whoever>\Documents\My Games\<GameName> directory, where both My Games and <GameName> may not yet exist. Here’s a workaround:

/// <summary>Creates all directories down to the specified path</summary>
/// <param name="directory">Directory that will be created recursively</param>
/// <remarks>
///   The provided directory must not be terminated with a path separator.
/// </remarks>
void createDirectoryRecursively(const std::wstring &directory) {
  static const std::wstring separators(L"\\/");

  // If the specified directory name doesn't exist, do our thing
  DWORD fileAttributes = ::GetFileAttributesW(directory.c_str());
  if(fileAttributes == INVALID_FILE_ATTRIBUTES) {

    // Recursively do it all again for the parent directory, if any
    std::size_t slashIndex = directory.find_last_of(separators);
    if(slashIndex != std::wstring::npos) {
      createDirectoryRecursively(directory.substr(0, slashIndex));
    }

    // Create the last directory on the path (the recursive calls will have taken
    // care of the parent directories by now)
    BOOL result = ::CreateDirectoryW(directory.c_str(), nullptr);
    if(result == FALSE) {
      throw std::runtime_error("Could not create directory");
    }

  } else { // Specified directory name already exists as a file or directory

    bool isDirectoryOrJunction =
      ((fileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0) ||
      ((fileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0);

    if(!isDirectoryOrJunction) {
      throw std::runtime_error(
        "Could not create directory because a file with the same name exists"
      );
    }

  }
}

This code is free for the taking and you can use it however you want.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.