mark@elsie.UUCP (Mark J. Miller) (10/03/84)
Our C compiler (4.1 BSD) will ignor CTRL L's (form feeds). This is nice because it allows one to ask for a new page at the begining of subroutines. It is also not documented, probably non-standard, and probably should be an error. How far back does this "feature" go? Is it in all, most, of just a few of the compilers out there. If it is universal, shouldn't it be documented? -- Mark J. Miller NIH/NCI/DCE/LEC UUCP: decvax!harpo!seismo!umcp-cs!elsie!mark Phone: (301) 496-5688
henry@utzoo.UUCP (Henry Spencer) (10/05/84)
> Our C compiler (4.1 BSD) will ignor CTRL L's (form feeds). This is nice > because it allows one to ask for a new page at the begining of subroutines. > It is also not documented, probably non-standard, and probably should be an > error. How far back does this "feature" go? Is it in all, most, of just a > few of the compilers out there. If it is universal, shouldn't it be > documented? ANSI C draft of 21 Aug 1984, section 2.0: "Space characters, horizontal tabs, new-lines, vertical tabs, form feeds, and comments ... -- collectively called *white space* -- are ignored except as they serve to separate tokens." So this particular feature can be assumed to be legitimate in future C compilers. Unfortunately, K&R's list of white-space characters is not as long, and does *not* include formfeed, so there are probably a good many current compilers out there that won't like it. On the other hand, simply removing all the formfeeds in a file is easy with any text editor worthy of the name, so it doesn't seem like a big stumbling block to portability. If you really want to be 100% portable with current compilers, put /* */ around the formfeeds. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
crm@duke.UUCP (Charlie Martin) (10/05/84)
Isn't ^L defined to be in the class of whitespace characters? If so, then the C compiler should ignore it because it ignores insignificant whitespace (multitabs or spaces between symbols, also (I think) therefore ^L etc.)
robert@erix.UUCP (Robert Virding) (10/05/84)
A simple way to make sure of getting a form feed before a function in a legal way is just to put it into a comment, /* ^L */.
dre@ptsfa.UUCP (Doug East) (10/06/84)
> Our C compiler (4.1 BSD) will ignor CTRL L's (form feeds). This is nice > because it allows one to ask for a new page at the begining of subroutines. > It is also not documented, probably non-standard, and probably should be an > error. How far back does this "feature" go? Is it in all, most, of just a > few of the compilers out there. If it is universal, shouldn't it be > documented? We have compiler on a Convergent Technologies Megaframe (sys5) which exhibits the same behaviour. It isn't documented either, as far as I can discern. Doug East (Pacific * Bell) {ihnp4,ucbvax,cbosgd,decwrl,amd70,fortune,zehntel}!dual!ptsfa!dre
rgh@inmet.UUCP (10/07/84)
#R:elsie:-400600:inmet:5000025:000:379
inmet!rgh Oct 5 11:09:00 1984
Form-feed is allowed as whitespace in every C compiler I know of.
This usage is recognized in the ANSI draft C standard, which says
"Space characters, horizontal tabs, new-lines, vertical tabs, form
feeds, and comments (described below) -- collectively called
white space -- are ignored except as they serve to separate tokens."
Randy Hudson
{ihnp4,harpo,ima}!inmet!rghbsa@ncoast.UUCP (Brandon Allbery) (10/07/84)
`Whitespace' means any of ' ', '\f', or '\n' -- so maybe the did document it and we didn't notice? (I don't have a copy of K&R so I don't know if they actually *say* whitespace -- can someone check?) --bsa
rmorgan@tikal.UUCP (R J Morgan) (10/11/84)
From K&R, Appendix A: C REFERENCE MANUAL, 'Lexical conventions': "Blanks, tabs, newlines, and comments (collectively, "white space")... Sorry, but K&R doesn't seem to support the formfeed argument.
Tli@usc-eclb.ARPA (10/11/84)
From: Tony Li <Tli@usc-eclb.ARPA> >`Whitespace' means any of ' ', '\f', or '\n' -- so maybe the did document >it and we didn't notice? (I don't have a copy of K&R so I don't know >if they actually *say* whitespace -- can someone check?) K+R says that whitespace is ' ', '\t', and '\n'. (pg. 156). Cheers, Tony ;-)
marc@wlcrjs.UUCP (Marc Lavine) (10/13/84)
> Our C compiler (4.1 BSD) will ignor CTRL L's (form feeds). This is nice > because it allows one to ask for a new page at the begining of subroutines. > It is also not documented, probably non-standard, and probably should be an > error. How far back does this "feature" go? Is it in all, most, of just a > few of the compilers out there. If it is universal, shouldn't it be > documented? Your compiler probably includes form feeds in its definition of white space, although K&R doesn't seem to recognize them as such (see pg. 179). -- Marc Lavine uucp: ...ihnp4!wlcrjs!marc