On 08/05/2011 09:19 PM, Prof Brian Ripley wrote:
On Fri, 5 Aug 2011, Duncan Murdoch wrote:
On 11-08-05 12:09 AM, Alexandre Aguiar wrote:
Hi,
When a function returns a SEXP of type LGLSXP (logical) to signal
whether
it succeeded or failed, how is it intrepreted? Is it like C where
SUCCESS
= 0 or other value?
Usually TRUE is used to signal success. TRUE is non-zero.
Strictly, TRUE is not numeric: it is coerced to 1 when coerced to a
numeric value.
If you are looking at C level at the SEXP: don't as the internal
representation is just that: 'internal and subject to change'.
There is no C convention to use 0 for success: that is a Unix convention
for status values as returned by exit(), and even there the man page
will advise you to use the symbol EXIT_SUCCESS. Other OSes do differ.
see p164 Kernighan & Ritchie.
Jim
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