* gcc question about the embedded type definitions
@ 2004-12-03 6:51 Wei ZHANG
2004-12-03 9:20 ` Nathan Sidwell
0 siblings, 1 reply; 4+ messages in thread
From: Wei ZHANG @ 2004-12-03 6:51 UTC (permalink / raw)
To: GCC Help
Hi,
I have a question on embedded type definitions.
If in a structure definition, another type is defined. e.g.
typedef struct S1 {
struct S2 {
int a;
}
} S1;
is the data type S2 visible outside S1? Originally i think it is not
visible outside.
But in gcc, I can declare a varible of type struct S2, and operate on
it. e.g.:
S2 b;
b.a = 100;
printf("result = %d\n", b.a);
That implies the name of the structure type S2 must be unique in the C
file. Am I right? Can anyone elaborate on this? Thanks!
Best Regards,
Zhang Wei
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: gcc question about the embedded type definitions 2004-12-03 6:51 gcc question about the embedded type definitions Wei ZHANG @ 2004-12-03 9:20 ` Nathan Sidwell 2004-12-03 11:29 ` Serge Fukanchik 0 siblings, 1 reply; 4+ messages in thread From: Nathan Sidwell @ 2004-12-03 9:20 UTC (permalink / raw) To: Wei ZHANG; +Cc: GCC Help Wei ZHANG wrote: > Hi, > > I have a question on embedded type definitions. > > If in a structure definition, another type is defined. e.g. > > typedef struct S1 { > struct S2 { > int a; > } > } S1; > > is the data type S2 visible outside S1? Originally i think it is not > visible outside. in C it is visible, in C++ it is not. in C it declares a field of the outer struct, in C++ it declares a nested member. Your example is neither C not C++ though, as it is missing at least a semi colon. nathan -- Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: gcc question about the embedded type definitions 2004-12-03 9:20 ` Nathan Sidwell @ 2004-12-03 11:29 ` Serge Fukanchik 2004-12-03 11:38 ` Nathan Sidwell 0 siblings, 1 reply; 4+ messages in thread From: Serge Fukanchik @ 2004-12-03 11:29 UTC (permalink / raw) To: Nathan Sidwell; +Cc: Wei ZHANG, GCC Help Nathan Sidwell wrote: > in C it is visible, in C++ it is not. ?! In C++ all members of `struct' are public by default and hence fully accessible. You have to explicitly say `private:'. On the other side all members of `class' are private by default. You can not access them unless you say `public:' --- Serge ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: gcc question about the embedded type definitions 2004-12-03 11:29 ` Serge Fukanchik @ 2004-12-03 11:38 ` Nathan Sidwell 0 siblings, 0 replies; 4+ messages in thread From: Nathan Sidwell @ 2004-12-03 11:38 UTC (permalink / raw) To: Serge Fukanchik; +Cc: Wei ZHANG, GCC Help Serge Fukanchik wrote: > Nathan Sidwell wrote: > >> in C it is visible, in C++ it is not. > > ?! In C++ all members of `struct' are public by default > and hence fully accessible. You have to explicitly say `private:'. you have to qualify their names -- they are not visible in the global namespace. The question was about their visibility not their accessibility. nathan -- Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2004-12-03 11:38 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2004-12-03 6:51 gcc question about the embedded type definitions Wei ZHANG 2004-12-03 9:20 ` Nathan Sidwell 2004-12-03 11:29 ` Serge Fukanchik 2004-12-03 11:38 ` Nathan Sidwell
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