levy@ttrdc.UUCP (Daniel R. Levy) (04/26/88)
> Before > trying to dump on DEC a la IBM, however, keep in mind that IBM sells primarily > to business customers, who don't know a goto from a RAM chip, whereas DEC > sells primarily to technical installations and research institutions. Oops. Someone pointed out to me that DEC's biggest VMS market is commercial, not technical. Seems hard to believe in the face of IBM's stranglehold on that market, but I'll take it at face value. Darn all those insurance companies and banks, they had to go buy DEC and make me look like a fool. :-) To the best of my knowledge: my point still stands to the effect that DEC has a helluva lot of VMS VAXes out there in technical fields, and that there are far more VAXes in those fields running VMS than are running the UNIX operating system, if a survey in a not-too-ancient _DEC_Professional_ is to be believed. (Though on behalf of AT&T, I hope this will evolve to be the other way around, or even better, VMS VAXES will eventually be outnumbered by 3B4000s or their successors running UNIX System V [dreamin' on...] :-) ). -- |------------Dan Levy------------| Path: ihnp4,<most AT&T machines>!ttrdc!levy | AT&T | I'm not a real hacker, but I play one on | Data Systems Group | USENET. If you think that AT&T endorses |--------Skokie, Illinois--------| my opinions, I've a nice bridge to sell ya.
blarson@skat.usc.edu (Bob Larson) (04/26/88)
In article <2615@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes: >far more VAXes in those fields running VMS than are running the UNIX operating >system, if a survey in a not-too-ancient _DEC_Professional_ is to be believed. A survey in a VMS publication indicates most of its readers use VMS is hardly surprising or any kind of indication of the ratio of VMS to UNIX vaxen. -- Bob Larson Arpa: Blarson@Ecla.Usc.Edu blarson@skat.usc.edu Uucp: {sdcrdcf,cit-vax}!oberon!skat!blarson Prime mailing list: info-prime-request%fns1@ecla.usc.edu oberon!fns1!info-prime-request
walterm@hpwrce.HP.COM (Walter Murray) (05/17/91)
steve@taumet.com (Stephen Clamage) writes: > aj3u@wilbury.cs.virginia.edu (Asim Jalis) writes: >>What is the difference between these two (pf is a pointer to a >>function, and hello is a function): >>pf = hello; >>and >>pf = &hello; > There is no difference. The oddity is this: A function designator > appearing in an expression context is replaced by the address of the > function, making a pointer-to-function. Attempts to take the address > of the function designator are ignored. So > hello > &hello > &&&&&&&&&&&&&&&&hello > are all equivalent. I would say that an attempt to take the address of a function designator is honored, but is unnecessary because it's a conversion that is done automatically anyway. And the third example has problems. First, && will be taken as a logical AND operator, resulting in a syntax error. We can correct that by writing: & & & & & & & & & & & & & & & &hello; But it seems to me this is still illegal. When & is applied to a function designator, the result is a pointer to a function and is not an lvalue. This pointer-to-function does not get converted back to a function designator. Applying the next & should cause a diagnostic, because the operand of & must be either a function designator or an lvalue, and &hello is neither. Relevant sections in the Standard are 3.2.2.1 and 3.3.3.2. > Similarly, when you dereference a pointer-to-function, you get a > function designator, which is replaced by pointer-to-function. > Consequently, > pf() > (*pf)() > (****************pf)() > are all equivalent. Right. Walter Murray ----------