how has C bitten you?

Alan T. Bowler [SDG] atbowler at watmath.UUCP
Mon Aug 12 04:57:22 AEST 1985


In article <505 at brl-tgr.ARPA> mbarker at BBNZ.ARPA (Michael Barker) writes:
>>So, printf can never get a float as an argument, it always gets a double.
>>Therefore, %lf or %F are meaningless to printf.
>>
>>Brian Jones  aka  {ihnp4,}!drutx!qwerty  @  AT&T-IS
>
>Brian (et al) - the reasoning is correct, but printf could easily be changed to
>accept %lf or %F (or any useful convention) as formatting directions for a
>value with the knowledge that the value will *actually* be a double.  Let's try
I thought that the implicit promotion of float to double on passing
an argument was one of the things that was going away with the
new C standard.   It certainly has been high on my personal hit list.
  I grant that there was a reasonable case for it when C was just for
PDP-11's.  But these days when there is a good possibility that
floating point is being handled by a software implementation of
the IEEE standard, it is a loser.  In this situation the conversion
between float and double is a reasonably expensive operation,
and really should only be done when the programmer explicitly asks for it.



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