In Ruby, how do I replace the question mark character in a string?

Question

In Ruby, I have:

require 'uri'
foo = "et tu, brutus?"
bar = URI.encode(foo)      # => "et%20tu,%20brutus?"

I'm trying to get bar to equal "et%20tu,%20brutus%3f" ("?" replaced with "%3F") When I try to add this:

bar["?"] = "%3f"

the "?" matches everything, and I get

=> "%3f"

I've tried

bar["\?"]
bar['?']
bar["/[?]"]
bar["/[\?]"]

And a few other things, none of which work.

Answer 1

require 'cgi' and call CGI.escape