On 3/6/2007 12:15 PM, [EMAIL PROTECTED] wrote:
> Full_Name: Stephanie MAHEVAS
> Version: 2.4.1
> OS: Windows NT
> Submission from: (NULL) (134.246.55.50)
>
>
>
> the two following instructions provide a synthax error :
>
> if ( 5 > 4 ) cat("ok1")
> else cat("ok2")
>
> and
>
> if ( 5 > 4 ){ cat("ok1")}
> else cat("ok2")
>
> whereas these ones don't
>
> if ( 5 > 4 ) cat("ok1") else cat("ok2")
>
> and
>
> if ( 5 > 4 ){ cat("ok1")
> }else cat("ok2")
>
> It looks like a parser problem. If else is not on the same line as if or if
> the
> end of block statement of if } is not paste to else, else does not seem linked
> with if
This is a documented "feature" of the language, not a bug. (See the
language guide, section 3.2.1 "if", around the 4th paragraph.)
It arises because R tries to evaluate a statement as soon as it is
complete, and
if ( 5 > 4 ) cat("ok1")
is a complete statement. You can get the behaviour you want by wrapping
the whole think in curly brackets so that R doesn't start evaluating too
early, e.g.
> {
+ if ( 5 > 4 ) cat("ok1")
+ else cat("ok2")
+ }
ok1>
Duncan Murdoch
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
