root@wotk.UUCP (Superuser) (08/02/90)
I was reading the August issue of The C Users Journal and came across
this in Rex Jaeschke's article -
( The ability to subscript a pointer gives rise to the identity )
( )
( a[i] is equivalent to *(a + i) )
( )
( It also allows expressions such as )
( )
( "abcd"[i] and f()[j] )
^^^^^
I thought this was taboo. What's the story on this?
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Roswell, GA 30076inst182@tuvie (Inst.f.Techn.Informatik) (08/02/90)
root@wotk.UUCP (Superuser) writes: >I was reading the August issue of The C Users Journal and came across >this in Rex Jaeschke's article - >( It also allows expressions such as ) >( ) >( "abcd"[i] and f()[j] ) > ^^^^^ >I thought this was taboo. What's the story on this? Why should this be taboo? Provided f is declared as sometype * f (void) it returns a pointer to sometype, and I can subscript that pointer like any other pointer. After all, in C arrays are treated like pointers to their first element in almost any context. (Hope, the wording is correct, I don't want to go through that Arrays-are-not-pointers discussion again) Peter J. Holzer | _ | Peter J. Holzer | Think of it | | |_|_) | Technische Universitaet Wien | as evolution | | | | | hp@vmars.tuwien.ac.at | in action! | | __/ | ...!uunet!mcsun!tuvie!vmars!hp | Tony Rand |
steve@taumet.com (Stephen Clamage) (08/02/90)
nickh@wotk.UUCP (Nick Hennenfent) writes: >( "abcd"[i] and f()[j] ) > ^^^^^ >I thought this was taboo. What's the story on this? In ANSI C, it's perfectly ok, as long as f() is declared to return a pointer type. Many earlier C compilers did not support this, however, and its portability was not guaranteed. Any conforming ANSI compiler must allow it. Similarly, if f() returns a struct type with member x, you could write f().x, and if f() returns a pointer to a function, you could write f()(). I make no comment on whether any of this is good programming practice. -- Steve Clamage, TauMetric Corp, steve@taumet.com
dbk@mimsy.umd.edu (Dan Kozak) (08/04/90)
From article <1741@tuvie>, by inst182@tuvie (Inst.f.Techn.Informatik): >>( "abcd"[i] and f()[j] ) > Provided f is declared as > sometype * f (void) > it returns a pointer to sometype, and I can subscript that pointer like > any other pointer. Or if the declarations are int f (void); sometype j[SOMECONSTANT]; -- #dan Clever: dbk@mimsy.umd.edu | "For I was rolled in water, Not-so-clever: uunet!mimsy!dbk | I was rolled out past the pier" - MoB