need info: %r in printf

Henry Spencer henry at utzoo.UUCP
Fri Oct 14 06:03:23 AEST 1983

The reason (well, I think the major reason) why %r has gone away in
recent years is that it is not really portable.  The trick of calling
a routine with a variable number of parameters, while the routine
declares only one parameter and invokes printf %r with the address
of that parameter, is nifty and neat but absolutely requires some
highly machine-dependent assumptions about calling sequences.  There
is no truly machine-independent way to do this trick without help from
the language, help which C does not provide.  The only thing you can
really do about it is to sprintf into a string and then pass that.
(Yes, I know, it's not as convenient.)

Please, no questions about why a machine-dependent construct like this
is in DECUS C.  Either they didn't know what they were doing, or they
didn't care (anyone using a DEC operating system obviously isn't worried
about portability anyway, right?).
				Henry Spencer @ U of Toronto Zoology

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