Many thanks Simon for your response
>> Identifying the source of the message is a non-trivial problem because there are a large number of calls to printf and fprintf etc in several thousands of lines of code spread over many different *.c files.
>>
> There should be none, so apparently you have broken the rules quite a lot ;). This is not a new rule, R just got better at identifying the transgressions. Number of lines in your code is quite irrelevant - that's why there is grep and the search function in editors.

Well, that wouldn't be the first time I've broken rules ;0)

But, how bad could the consequences of my misbehaviour be here?  Are we 
talking about crashing R or just messing the output a little?

In Writing R Extensions (current on-line version) the worst they say 
about printf is

[QUOTE]
The most useful function for printing from a C routine compiled into R 
is |Rprintf|. This is used in exactly the same way as |printf|, but is 
guaranteed to write to R's output (which might be a GUI console rather 
than a file, and can be re-directed by |sink|).
[UNQUOTE]

and both printf and fprintf are used in section 8.2.2 in the rtest.c 
example. Also, the manual does not say explicitly what fprintf should be 
replaced with.

Come to think of it... my package performs MCMC and uses fprintf to 
write samples to an output file. I have noticed that once in each nth 
blue-moon (for large n) a single line of output has been dropped or 
scrambled. More frequently, the updates of the output file seem to lag 
behind the progress of the algorithm's principal loop - for example, 
file size becomes non-zero much later than I expect. I never understood 
this behaviour or saw how to rectify it. Perhaps replacing fprintf with 
something else could "guarantee" the end of this undesirable behaviour? 
Great!

Is there a "safe" way to re-write the following?

fprintf(fMCMCout, "%d %e %e ", iteration, posteriorLoglik, parameter);
if (numberRandomEffects > 1) {
   for (k=0; k < numberRandomEffects; k++) {
     fprintf(fMCMCout, "%e ", randomEffects[k]);
}
fprintf(fMCMCout,"\n");

This is really a question of 2 parts
1) what is the best replacement of fprintf in the above?
and
2) Writing R Extensions says "It is wise to write complete lines 
(including the |"\n"|) before returning to R.", so is it legal to defer 
\n as in the example above?

many thanks
David





-- 
David Pleydell,
INRA,
UMR-1351 CMAEE,
Domaine Duclos,
Prise D'eau,
97122 Petit Bourg,
Guadeloupe
dpleydell@antilles.inra.fr
pleydell@cirad.fr
Tel +33 5 90 25 54 42
Fax +33 5 90 94 03 96


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