问题描述
只是想知道这样铸造是否安全:
Just wondering if it's safe to cast like this:
char **cpp;
// ... allocation and what not
void *vp = (void *)cpp;
// ...
cpp = (char **)vp;
应该使用void **还是void *可以吗?这可以在我的几个盒子上正常工作，但想知道它是否会在某些系统上引起问题.
should a void ** be used or is void * fine? This works on a couple of my boxes without issue but was wondering if it could cause problems on certain systems.
推荐答案
强制转换始终是安全的，只要指针有效，则取消引用是安全的.唯一打算使用void **的情况是，当您打算取消引用以获得void *时.
The cast is always safe, dereferencing it is safe as long as the pointer is valid.The only case where you'd use a void ** is when you plan to dereference it to get a void *.
但是，除非您执行指针算术运算，否则它实际上并不重要.正如您在 http://codepad.org/UcZUA0UL 上看到的那样，无论是否使用void*或void **.在实际使用指针之前，无论如何都要将其转换回char **-因此在void -ish时永远不会取消引用它.
However, unless you do pointer arithmetics it won't really matter. As you can see on http://codepad.org/UcZUA0UL it works fine no matter if you use void* or void **. Before you actually use the pointer you are going to cast it back to char ** anyway - so it is never dereferenced while it's void-ish.
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