NA in C/C++
Dear Prof Ripley Thank you very much for your fast response. I did not realize that meanwhile CRAN has official documents. Section 3.7.3 mentions macros in "Arith.h" for handling NAs. I assume that these macros can also be used in normal C programs.
From your answer I assume that C-libraries like the STL-library are normally
not able to deal with NAs? Best regards Christian Stratowa
Prof Brian D Ripley wrote:
On Sun, 28 May 2000 cstrato at EUnet.at wrote:
Dear R-people Sorry for asking a question only indirectly related to S/R but since data containing NA values can so easily be handled in S/R, and you can write functions for S/R in C, my question is: How do you handle data containing NA in C/C++ ? Although I know that IEEE floating point arithmetics supports NaN and Inf, I cannot find any information about this (e.g. in any of my many C++ books) Thank you in advance for your help Christian Stratowa, Vienna
It's in Writing R Extensions (sections 3.7.3 and 4.4 in the copy I have to hand, but it's in the concept index). You cannot assume in R that NA is represented by an NaN, although on most machines it is. Conversely, most NaNs are not NA. -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595
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