ed

[Steve Summit]

Has anyone else been bothered by the following limitation of ed? 
There is no easy way to specify the second (or third or
fourth...) instance of a pattern on a line in an s command. 
(There is probably some horrendous way to do it with \( but it
certainly wouldn't be easy.)  For instance, I have the line

	printf("c[i] = %d = 0%o = '%c'\n", c[i], c[i], c[i]);

and I want to change the last c[i] to c[i++].  In this case I
could distinguish it with the trailing ')', but it's not always
that easy.

(Please don't ask me why I'm using ed.  I think most people would
agree that there are some global type edits that are still best
done with a line based editor.  Of course I use a screen editor
most of the time.)

I've actually considered adding this feature myself, but I
haven't figured out a syntax and I'm not anxious to dive into the
regular-expression code.

Has anyone figured out a decent way to do this with vanilla ed?
Has anyone implemented it?  Do the (apparently) ed-compatible ex
and vi have a pattern-match extension to make it easier?

                                  Steve Summit
                                  tektronix!tekmdp!bronze!stevesu