string comparison

It is not safe to rely on pointer comparisons until R 2.8.0.  Currently it 
is easy to get CHARSXPs that are not in the cache: it is not impossible in 
2.8.0, but you have to know how to 'break and enter'.

In your code you are comparing a CHARSXP and a SYMSXP.  You want to 
use charChance = mkChar("chance") and then make it precious 
(R_PreciousObject).

On Thu, 7 Aug 2008, Kjell Konis wrote:

Hi,

I have a package where I do things like this a lot:

if(strncmp(CHAR(asChar(Scategory)), "chance", 6) == 0)
  category = h_category_chance;
else if(strncmp(CHAR(asChar(Scategory)), "utility", 7) == 0)
  category = h_category_utility;
else if(strncmp(CHAR(asChar(Scategory)), "decision", 8) == 0)
  category = h_category_decision;
else if(strncmp(CHAR(asChar(Scategory)), "instance", 8) == 0)
  category = h_category_instance;
else
  category = h_category_error;

I would like to replace the strncmps with pointer comparisons so I set up 
some global variables in the R_init_myDLL function like this:

charChance = install("chance")
<etc.>

but I can't seem to get the comparison to work. I want to do something like

if(CHAR(asChar(Scategory)) == charChance)
  category = h_category_chance;

but category always ends up being h_category_error. Any pointers would be 
appreciated.

Thanks,
Kjell