On Mon, Oct 20, 2014 at 2:17 PM, Gustaf Granath <gustaf.gran...@gmail.com>
wrote:
> Hi
> Im trying to use some C++ functions in R. However, these functions are
> build around unsigned char* variables (1D array). I have for example a
> large matrix in R that represents black (e.g. 1-bit image, 0 and 1s). I
> cant find a solution to convert a character vector into unsigned char*
> within Rcpp. Im new to Rcpp and C++ so I might have missed something
> obvious here. Please direct me to resources on this topic (google did not
> help much).
>
> A start:
>
> SEXP test(SEXP cM){
> CharacterVector Vc(cM);
> int n = Vr.size();
> RawVector x(n); //is this the same as unsigned char* ?
> //I tried to fill it with char*(Mr) but I
> didnt succeed
> }
>
I tend to go through the standard library as its less of a black box. Try
creating a std::string and appending your chars to that string. Then call
obj.c_str() to get the C-style array of chars. Or push the chars onto a
std::vector and do something like &obj[0] to get a 1-D array.
THK
>
> Thanks,
>
> Gustaf
>
> --
> Gustaf Granath (PhD)
> Post doc
> McMaster University
> School of Geography & Earth Sciences
>
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