R devel - Jan 2011 - C code hanging and printing everything at the end

Hi,

I am currently writing an extension for R and have the need to include some C
code. If I call the code with a large amount of data then it can take several
minutes to complete.

The C code prints out after a certain iteration hence letting the user know it
hasn't crashed.

When running in R this generally does not happen and all is printed out at the
end once the program has completed successfully.

I am using Rprintf() to print out the required output.

e.g. Something simple which illustrates my point

for(int i=0; i<10000; i++){
	#Calculations
	if (i%1000==0){
		Rprintf("Step %d\n",i)
	}
}

All I get during the program is the OS X spinning wheel in R. Is there any way
to print out as the program is running?

Thanks,
Rob

On Jan 4, 2011, at 11:41 AM, Robert Lowe wrote:
> Hi,
> 
> I am currently writing an extension for R and have the need to include some
C code. If I call the code with a large amount of data then it can take several
minutes to complete.
> 
> The C code prints out after a certain iteration hence letting the user know
it hasn't crashed.
> 
> When running in R this generally does not happen and all is printed out at
the end once the program has completed successfully.
> 
> I am using Rprintf() to print out the required output.
> 
> e.g. Something simple which illustrates my point
> 
> for(int i=0; i<10000; i++){
> 	#Calculations
> 	if (i%1000==0){
> 		Rprintf("Step %d\n",i)
> 	}
> }
> 
> All I get during the program is the OS X spinning wheel in R. Is there any
way to print out as the program is running?
> 
You want to add R_CheckUserInterrupt(); so that the system has a chance to run
the event loop and thus display the result. But the implication is that you may
be interrupted so make sure R controls any memory allocations you have made.

Cheers,
Simon