VIM: How to preserve case for search and replace [duplicate]

Question

Possible Duplicate:
Case preserving substitute in Vim

Is it possible to do a search and replace in vim that preserves the case of the search term? This was a useful feature in intelliJ that I miss.

For instance, something like:

:s/[uU]ser/[pP]erson/ (obviously, this doesn't work)

Such that:

user->person
User->Person

Another example with multiple characters to preserve:

:s/[mM]y[uU]ser/[tT]his[pP]erson/g

Such that:

myuser->thisperson
myUser->thisPerson
MyUser->ThisPerson

Answer 1

There are a few approaches that can be taken. If you want to stick with basic Vim functionality, you can do something like

:%s/[uU]ser/\=submatch(0) ==# 'user' ? 'person' : 'Person'/g

If you have Vim built with Perl bindings, you can make use of :perldo. Depending on the length of the matching/replacing words and where the case you want to preserve is, this may or may not work.

:perldo s/(user)/"\L$1" ^ $1 ^ 'person'/ieg

Or you can make use of one of the various scripts that implement such functionality.