Interactive search/replace regex in Vim?

Question

I know the regex for doing a global replace,

     %s/old/new/g

How do you go about doing an interactive search-replace in Vim?

Answer 1

I usually use the find/substitute/next/repeat command :-)

/old3snewn.n.n.n.n.n.n.

That's find "old", substitute 3 characters for "new", find next, repeat substitute, and so on.

It's a pain for massive substitutions but it lets you selectively ignore some occurrences of old (by just pressing n again to find the next one instead of . to repeat a substitution).