Super User is a question and answer site for computer enthusiasts and power users. It only takes a minute to sign up.
Sign up to join this community
In Emacs, how to comment a block of text, i.e. how to indent a block of text rightward by n whitespace characters and put a chosen character sequence, say ##, at the beginning of each line?
Original
foo
bar foobar
foo bar
Desired:
# foo
# bar foobar
# foo bar
comment-dwin doesn't allow me to choose arbitrary character sequence.One way is to use string-rectangle (C-x r t).
Mark the block, then call string-rectangle and give ## as a string to insert.
C-M-@ 3) move cursor to end 4) C-x r t 5) type prefix character sequence, such as ## , press ENT
Depending on what mode you are running (e.g. CC Mode, Lisp Mode) you can select the region and then use the command comment-region (usually bound to C-c C-c. If everything is set correctly, it should use the appropriate comment characters for the type of file you are editing.
M-; is a more general commenting command. When there is no active region, it inserts a comment (after any statements on the line, and lined up with the comment column). When a region is selected, it behaves like comment-region. When there is no active region, comment-region does not insert a comment.
Jan 19, 2012 at 19:43
comment-region, unlike comment-dwim (which is M-; by default) lets you flexibly nest and unnest block comments. Use plain C-u to unnest one level of nesting. (I bind C-x C-; to comment-region. Actually, I bind it to comment-region-lines from misc-cmds.el.)
You want to select the code region and then M-;
