int list_file(string path)
{
    DIR *dir;
    struct dirent *ent;
    char  *c_style_path;
    c_style_path = new char[path.length()];
    c_style_path = (char *)path.c_str();
    dir = opendir (c_style_path);
    if (dir != NULL) {

        /* print all the files and directories within directory */
        while ((ent = readdir (dir)) != NULL) {
            if(ent->d_type == DT_DIR && (strcmp(ent->d_name,".")!=0) && (strcmp(ent->d_name,"..")!=0))
            {
                string tmp = path + "\" + ent->d_name;
                list_file(tmp);
            }
            else
            {
                cout<<ent->d_name<<endl;
            }
        }
        closedir (dir);
    } else {
        /* could not open directory */
        perror ("");
        return EXIT_FAILURE;
    }
    delete [] c_style_path;
    return 0;
}

c_style_path = (char *)path.c_str();
//...
delete[] c_style_path;

dir = opendir (path.c_str());