Rectangle functions in emacs

Question

I\'ve read in several places that the rectangle functions in emacs are very useful. I\'ve read a bit about them, and I can\'t quite figure why. I mean, when you want to kill

Answer 1

In emacs24+ there's also function for numbering lines:

(rectangle-number-lines START END START-AT &optional FORMAT)

Insert numbers in front of the region-rectangle.

START-AT, if non-nil, should be a number from which to begin
counting.  FORMAT, if non-nil, should be a format string to pass
to `format' along with the line count.  When called interactively
with a prefix argument, prompt for START-AT and FORMAT.

It is binded to C-x r N by default.