Mitch Tishmack schrieb:
> In short I see this behavior:
> 
> "Stuhlu".sub(/u/,'?')
> => "St?hlu"
> "Stuhlu".reverse.sub(/u/,'?').reverse
> => "Stuhl\274\303"
> "Stuhlu".reverse.sub(/u/,'?').split(//).reverse.join
> => "Stuhl?"
> 
> The general goal is to sub the final "u" in that word with an  umlauted 
> version and not the first.
> ...
> Am I  mising a 
> Regexp option that would make the final match work?

Can't help with the reverse behaviour, but if you want to substitute 
single letters only the following regexp should work:

   "Stuhlu".sub(/u(?=[^u]*$)/,'?')

Regards,
Pit