[R] Capturing output of a C executable

[Jeff Newmiller]

You really need to read the "Writing R Extensions" document. It warns you against performing I/O from C code linked to R.

You probably ought to read the Posting Guide, also, since this question is off topic here 
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Sent from my phone. Please excuse my brevity.

On February 2, 2014 5:09:33 PM PST, Dennis Fisher <fisher at plessthan.com> wrote:
>R 3.0.1
>OS X
>
>Colleagues,
>
>I am experimenting with incorporating C code into R.  After compiling
>the C code with: 
>	R CMD SHLIB -o FILE.so FILE.c
>and executing:
>	dyn.load(“FILE.so”)
>(without any errors), I execute the following R functions in a terminal
>window:
>	READSAS 	<- function(sourcefile) .C("readsas", sourcefile) 
>	OUTPUT 		<- READSAS("../SASFILES/sdrug.sas7bdat") 
>R / C then reads a sas7bdat file and sends the contents to the terminal
>window.
>
>I expected OUTPUT to contain the text that appear in the terminal
>window (i.e., the contents of the file).  But, that is not the case;
>OUTPUT contains:
>	[[1]]
>	[1] "../SASFILES/sdrug.sas7bdat"
>It is not clear to my how to capture that appears in the terminal
>window.
>
>Ultimately, I may need to modify the C code so that the output goes to
>a file, which I then read into R.  However, it would be better if I did
>not need to modify the C code.
>Does anyone have any ideas of how I can capture this output within R?
>
>Dennis
>
>Dennis Fisher MD
>P < (The "P Less Than" Company)
>Phone: 1-866-PLessThan (1-866-753-7784)
>Fax: 1-866-PLessThan (1-866-753-7784)
>www.PLessThan.com
>
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