File.dirname(file_name ) → dir_name

Returns all components of the filename given in file_name except the last one. The filename must be formed using forward slashes (``/’’) regardless of the separator used on the local file system.

File.dirname("/home/gumby/work/ruby.rb")   #=> "/home/gumby/work"

Source Code

/*
*  call-seq:
*     File.dirname(file_name ) -> dir_name
*  
*  Returns all components of the filename given in <i>file_name</i>
*  except the last one. The filename must be formed using forward
*  slashes (``<code>/</code>'') regardless of the separator used on the
*  local file system.
*     
*     File.dirname("/home/gumby/work/ruby.rb")   #=> "/home/gumby/work"
*/

static VALUE
rb_file_s_dirname(klass, fname)
   VALUE klass, fname;
{
   const char *name, *root, *p;
   VALUE dirname;

   name = StringValueCStr(fname);
   root = skiproot(name);
#ifdef DOSISH_UNC
   if (root > name + 1 && isdirsep(*name))
       root = skipprefix(name = root - 2);
#else
   if (root > name + 1)
       name = root - 1;
#endif
   p = strrdirsep(root);
   if (!p) {
       p = root;
   }
   if (p == name)
       return rb_str_new2(".");
#ifdef DOSISH_DRIVE_LETTER
   if (has_drive_letter(name) && isdirsep(*(name + 2))) {
       const char *top = skiproot(name + 2);
       dirname = rb_str_new(name, 3);
       rb_str_cat(dirname, top, p - top);
   }
   else
#endif
   dirname = rb_str_new(name, p - name);
#ifdef DOSISH_DRIVE_LETTER
   if (has_drive_letter(name) && root == name + 2 && p - name == 2)
       rb_str_cat(dirname, ".", 1);
#endif
   OBJ_INFECT(dirname, fname);
   return dirname;
}