c - 在取消引用 void 指针后转换为 int 是否正确？

Question

void* aPtr = NULL;  // we don't yet know what it points to.
...
aPtr = &height;     // it has the address of height, but no type yet.
...
int h = (int)*aPtr; // with casting, we can now go to that address
                    // and fetch an integer value.

( Learn C Programming; Jeff Szuhay )

'with casting, we can now go [...]'

问题是 - 我们真的可以吗？

Answer 1

Dereferencing and Casting Void Ptr (Learn C Programming, Jeff Szuhay)

'with casting, we can now go [...]'

The question is - can we really?

是的，但是显示的代码没有进行任何解除引用。好吧，它尝试取消引用 void* 并将结果转换为 int。这不是应该做的。您必须先转换为 int*，然后 取消对 int* 的引用。

int h = *(int*)aPtr;    // now dereferenced ok (assuming `height` is an `int`)
//      ^   ^
//      |   |
//      |  proper cast
//      |
// dereferencing the right thing