获取文件扩展名

我如何改进以下代码，以便打印文件以用corect extenstion示例打印一个文本。这个"测试"

DIR *dir;
struct dirent *ent;
if ((dir = opendir ("/home/gabriel/C workspace/work1/oopproj/Debug/server")) != NULL) {
  /* print all the files and directories within directory */
  while ((ent = readdir (dir)) != NULL) {
    if( ! ( (strcmp (ent->d_name ,".") == 0) || (strcmp (ent->d_name ,"..") == 0 ) ) )
        printf ("%sn", ent->d_name);
  }
  closedir (dir);
} else {
  /* could not open directory */
  perror ("");
  return 0;
}