How do I duplicate a whole line in Emacs?

Question

I saw this same question for VIM and it has been something that I myself wanted to know how to do for Emacs. In ReSharper I use CTRL-D for this action. What is the least num

Answer 1

I write one for my preference.

(defun duplicate-line ()
  "Duplicate current line."
  (interactive)
  (let ((text (buffer-substring-no-properties (point-at-bol) (point-at-eol)))
        (cur-col (current-column)))
    (end-of-line) (insert "\n" text)
    (beginning-of-line) (right-char cur-col)))
(global-set-key (kbd "C-c d l") 'duplicate-line)

But I found this would have some problem when current line contains multi-byte characters (e.g. CJK characters). If you encounter this issue, try this instead:

(defun duplicate-line ()
  "Duplicate current line."
  (interactive)
  (let* ((text (buffer-substring-no-properties (point-at-bol) (point-at-eol)))
         (cur-col (length (buffer-substring-no-properties (point-at-bol) (point)))))
    (end-of-line) (insert "\n" text)
    (beginning-of-line) (right-char cur-col)))
(global-set-key (kbd "C-c d l") 'duplicate-line)