[Rd] Bug in sub? (PR#487)

[Peter Dalgaard BSA]

dtrenkler@nts6.oec.uni-osnabrueck.de writes:

> I suspect that there is bug in sub when using "?":
> 
> > string_"This is a bug!"
> >  sub("!", ", or isn't it?", string)
> [1] "This is a bug, or isn't it?"
> > string_"This is a bug?"
> >  sub("?", ", or isn't it?", string)
> [1] "This is a bug?"

Hmm. If there is a bug it may not where you think...

'?' is an operator of extended regular expressions, so you're not
looking for a question mark there: 

>  sub("\\?", ", or isn't it?", string)
[1] "This is a bug, or isn't it?"

>  sub("?", ", or isn't it?", ext=F, string)
[1] "This is a bug, or isn't it?"

One might expect that a null RE would always match the beginning of a
string, but it doesn't...

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
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