How can I make emacs highlight lines that go over 80 chars?

Question

I know there are solutions to making emacs show the 80 line column, but I don\'t want that sort of visual disturbance. I\'d just like to make it highlight a line if it\'s ov

Answer 1

There is a built-in package in emacs-goodies-el(recommend to install it in terminal) called highlight-beyond-fill-column.el, add this to your .emacs or init.el:

(setq-default fill-column 80)
(add-hook 'prog-mode-hook 'highlight-beyond-fill-column)
(custom-set-faces '(highlight-beyond-fill-column-face
                    ((t (:foreground "red" )))))

The text beyond fill-column which is 80 in the snippet will be highlighted with the color of red. You can set the face as you like.

Answer 2

This is not exactly what you wanted, but I had a similar problem and found this question/answer. All I wanted was to insert a visual guide, when I needed it. This is what I finally ended up with:

(defun insert-80 ()
    "Insert an 80-character-wide guide at beginning of line."
    (interactive)
    (beginning-of-line)
    (insert "0         1         2         3         4         5         6         7         |")
    (newline)
    (insert "01234567890123456789012345678901234567890123456789012345678901234567890123456789|")
    (newline)
)

Super simple, but sometimes very effective.