Comment Commands Comments Options for Comments
If you are typing a comment and wish to continue it on another line,
you can use the command C-M-j (
This terminates the comment you are typing, creates a new blank line
afterward, and begins a new comment indented under the old one. When
Auto Fill mode is on, going past the fill column while typing a comment
causes the comment to be continued in just this fashion. If point is
not at the end of the line when C-M-j is typed, the text on
the rest of the line becomes part of the new comment line.
To turn existing lines into comment lines, use the M-x comment-region command. It adds comment delimiters to the lines that start in the region, thus commenting them out. With a negative argument, it does the opposite---it deletes comment delimiters from the lines in the region.
With a positive argument,
comment-region duplicates the last
character of the comment start sequence it adds; the argument specifies
how many copies of the character to insert. Thus, in Lisp mode,
C-u 2 M-x comment-region adds `
;;' to each line. Duplicating
the comment delimiter is a way of calling attention to the comment. It
can also affect how the comment is indented. In Lisp, for proper
indentation, you should use an argument of two, if between defuns, and
three, if within a defun.
comment-padding specifies how many spaces
comment-region should insert on each line between the
comment delimiter and the line's original text. The default is 1.