Toggle between backslashes and forward slashes

toggle-backslash.el

(defun toggle-backslash-dwim (&optional start end)
  "Toggle slashes-backslashes for the active region.
If there's no active region START and END, it operates on the
current line."
  (interactive "r")
  (save-excursion 
    (unless (use-region-p)
      (cl-destructuring-bind (a . b)
          (bounds-of-thing-at-point 'line)
        (setf start a
              end b)))
    (with-restriction start end
      (goto-char start)
      (if (save-excursion (search-forward "/" nil t))
          (while (search-forward "/" nil t) (replace-match "\\\\" 'literal))
        (while (search-forward "\\" nil t) (replace-match "/"))))))

(global-set-key (kbd "C-c C-/") #'toggle-backslash-dwim)