typedef，structs和pointers [英] typedef, structs, and pointers
问题描述
有人可以解释为什么以下情况不可能吗？
typedef foobar {
int x;
foobar * next; / *为什么我们不能这样做？ * /
};
谢谢
Can someone please explain why the following is not possible?
typedef foobar {
int x;
foobar *next; /* why can''t we do this? */
};
Thanks
推荐答案
Steve Carter< st *** @ 127.0.0.1wrote：
Steve Carter <st***@127.0.0.1wrote:
>有人可以解释为什么以下是不可能的吗？
typedef foobar {
int x;
foobar * next; / *为什么我们不能这样做？ * /
};
谢谢
>Can someone please explain why the following is not possible?
typedef foobar {
int x;
foobar *next; /* why can''t we do this? */
};
Thanks
缺少''struct'' - 缺少typedef的新名称。
你可能想要这样的东西：
typedef struct foobar {
int x;
struct foobar * next;
} FooBar;
然后你可以使用
FooBar fb声明新的结构;
fb.next = ...;等等
Missing ''struct'' - Missing new name for typedef.
You probably want something like this:
typedef struct foobar {
int x;
struct foobar *next;
} FooBar;
Then you can declare new structures using
FooBar fb;
fb.next = ...; etc.
Roberto Waltman写道：
Roberto Waltman wrote:
缺少''struct'' - 缺少新的typedef的名称。
Missing ''struct'' - Missing new name for typedef.
哎呀，我忘了把''struct''放进去（虽然，我的意思是）。我仍然不知道为什么你不能使用typedef名称作为''next''指针，
虽然。
typedef struct foobar {
int x;
foobar * next;
};
Oops, I forgot to put ''struct'' in (though, I meant to). I still don''t
understand why you can''t use the typedef name for ''next'' pointer,
though.
typedef struct foobar {
int x;
foobar *next;
};
在文章< e9 ********** @ nntp.aioe.org> ;,, Steve Carter< st *** @ 127.0.0.1wrote：
In article <e9**********@nntp.aioe.org>, Steve Carter <st***@127.0.0.1wrote:
>有人可以解释为什么以下不可能吗？
>Can someone please explain why the following is not possible?
> typedef foobar {
int x;
foobar * next; / *为什么我们不能这样做？ * /
};
>typedef foobar {
int x;
foobar *next; /* why can''t we do this? */
};
因为我这么说 ;-)
typedef的typename在声明结束后才被视为存在，并且设计C的人没有
碰巧在本案例的前向引用中设计。他们在struct case的前向引用中做了
设计。我无法想象
当任何技术原因会阻止实施
对于typedef的前向引用，但是 - 或许 - 它会使
解析器显然比较棘手。
-
编程是在你忙于制定其他计划的时候发生的事情。
"Because I say so" ;-)
The typename for the typedef is not considered to exist until
the end of the declaration, and the people who designed C did not
happen to design in forward references for this case. They did
design in forward references for the struct case. I cannot think at
the moment of any technical reason that would block implementing
forward references for typedef, but -perhaps- it would make the
parser noticably trickier.
--
Programming is what happens while you''re busy making other plans.
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