sizeof（size_t）和sizeof（指针） [英] sizeof (size_t) and sizeof (pointer)
问题描述
是否必须？ ：
sizeof（size_t）> = sizeof（指针）
Alex Vinokur
电子邮件：alex DOT vinokur AT gmail DOT com
http://mathforum.org/library/view/10978 .html
http://sourceforge.net/users/alexvn
Alex Vinokur写道：
是吗不得不？ ：
sizeof（size_t）> = sizeof（指针）
编号size_t只需要足够大以代表
可以创建的最大对象数。
是指针的大小比@B $ b更大的实现甚至比可以分配的字符数（即
不是全部的指针中的位用于贡献
他的地址）。所有指针
的大小也不一样。
Ron Natalie写道：
< blockquote class =post_quotes>
并非所有指针
都需要相同的大小。
这是真的吗？我认为必须可以将任何
指针转换为void *。如果有不同大小的指针那么
它可能会有问题。
Juha Nieminen写道：
Ron Natalie写道：
>并非所有指针
都需要相同的大小。
这是真的吗？我认为必须可以将任何
指针转换为void *。如果有不同大小的指针
那么它可能会有问题。
如果void *至少与其中最大的一样大，该怎么办？如果
尺寸确实不同，那就没有意义，不是吗？
V
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Does it have to be? :
sizeof (size_t) >= sizeof (pointer)
Alex Vinokur
email: alex DOT vinokur AT gmail DOT com
http://mathforum.org/library/view/10978.html
http://sourceforge.net/users/alexvn
Alex Vinokur wrote:Does it have to be? :
sizeof (size_t) >= sizeof (pointer)
No. size_t only has to be big enough to represent the
maximum number of objects that could be created. There
are implementations where the sizeof the pointer is bigger
than even the number of chars that could be allocated (i.e,
not all the bits in the pointer were used to contribute
tot he address). It''s also not the case that all pointers
need to be the same size.
Ron Natalie wrote:It''s also not the case that all pointers
need to be the same size.Is that really so? I thought that it must be possible to cast any
pointer to and from a void*. If there were different-sized pointers then
it could be rather problematic.
Juha Nieminen wrote:Ron Natalie wrote:>It''s also not the case that all pointers
need to be the same size.
Is that really so? I thought that it must be possible to cast any
pointer to and from a void*. If there were different-sized pointers
then it could be rather problematic.What if void* is at least as large as the largest of them? If the
sizes do differ, it would makes sense, no?
V
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