R devel - Dec 2009 - a little bug for the function 'sprintf' (PR#14161)

Dear R-ers,

I am a gratuate student from South China University of Technology. I fond
the function 'sprintf' in R2.10.1 have a little bug(?):

When you type in the example codes:
> sprintf("%s is %f feet tall\n", "Sven", 7.1)
and R returns:

[1] "Sven is 7.100000 feet tall\n"

this is very different from the 'sprintf' function in C/C++, for in
C/C++,
the format string "\n" usually represents a new line, but here, just
the plain text "\n"!

Is it a bug, or a deliberate design?

Thanks for your attention!

Best wishes!

Yours sincerely,
Baoli Qin

	[[alternative HTML version deleted]]

baoliqin at gmail.com wrote:
> Dear R-ers,
> 
> I am a gratuate student from South China University of Technology. I fond
> the function 'sprintf' in R2.10.1 have a little bug(?):
> 
> When you type in the example codes:
> 
>> sprintf("%s is %f feet tall\n", "Sven", 7.1)
> 
> and R returns:
> 
> [1] "Sven is 7.100000 feet tall\n"
> 
> this is very different from the 'sprintf' function in C/C++, for in
C/C++,
> the format string "\n" usually represents a new line, but here,
just
> the plain text "\n"!

No, this is exactly the same as in C/C++. If you compare the result of 
sprintf to "Sven is 7.100000 feet tall\n" with strcmp() in C, they
will
compare equal.

 > s <- sprintf("%s is %f feet tall\n", "Sven", 7.1)
 > s
[1] "Sven is 7.100000 feet tall\n"
 > nchar(s)
[1] 27
 > substr(s,27,27)
[1] "\n"

The thing that is confusing you is that strings are DISPLAYED using the 
same escape-character mechanisms as used for input. Compare

 > cat(s)
Sven is 7.100000 feet tall
 >


> 
> Is it a bug, or a deliberate design?
Design, not bug (and please don't file as bug when you are in doubt.)
> Thanks for your attention!
> 
> Best wishes!
> 
> Yours sincerely,
> Baoli Qin
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
    O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

> When you type in the example codes:
> 
> > sprintf("%s is %f feet tall\n", "Sven", 7.1)
> 
> and R returns:
> 
> [1] "Sven is 7.100000 feet tall\n"
> 
> this is very different from the 'sprintf' function in C/C++, for in
C/C++,
> the format string "\n" usually represents a new line, but here,
just
> the plain text "\n"!
The function sprintf() produces a string, which is then printed
using R formatting. You probably expected the following.

  > cat(sprintf("%s is %f feet tall\n", "Sven", 7.1))
  Sven is 7.100000 feet tall

Compare also 

  > s <- sprintf("%s is %f feet tall\n", "Sven", 7.1)
  > cat(s)
  Sven is 7.100000 feet tall
  > print(s)
  [1] "Sven is 7.100000 feet tall\n"
  > 

PS.