NERD commenter : How to comment out a range

I'd do (in visual mode) :78v172G to select and highlight lines 78 to 172, then just ,c<space>.

It doesn't appear that NERDCommenter supports ranges, so Alex's answer would be correct, but he has a typo - it should be 78GV172G to select (note - no preceeding :), followed by your comment function ( in my case \cc).

Enter Visual mode <ctrl> + V, using your arrow keys, highlight the lines you want then /c<space> (perhaps you have another key binded for commenting).

Sexy C comments mode

Ranges of lines just work by default with visual selection + <leader>cc, tested on 2.5.2, as mentioned at: https://stackoverflow.com/a/1375070/895245

But above all, I want to highlight in this answer the "sexy mode" comments with <leader>cs, which generates nice C multiline comments.

For example, if you start with:

This is a c style sexy comment
So there!

then <leader>cs from visual selection transforms it into:

/* This is a c style sexy comment
 * So there! */

And you can also switch to non-compact mode by adding to your .vimrc:

let g:NERDCompactSexyComs = 0

which works as follows:

------------------------------------------------------------------------------

                                                         *'NERDCompactSexyComs'*
Values: 0 or 1.
Default 0.

Some people may want their sexy comments to be like this: >
    /* Hi There!
     * This is a sexy comment
     * in c */
<
As opposed to like this: >
    /*
     * Hi There!
     * This is a sexy comment
     * in c
     */

Another related format which might be of interest is the "Minimal comment map" accessible with <leader>cm and which produces:

/* Hi There!
   This is a sexy comment
   in C */

I wasn't able to find my preferred style unfortunately:

/* Hi There!
 * This is a sexy comment
 * in c
 */

so I opened: https://github.com/scrooloose/nerdcommenter/issues/379