C ++:数组长度的sizeof
假设我有一个名为 LengthOf(array) 的宏:
Let's say I have a macro called LengthOf(array):
sizeof array / sizeof array[0]
当我创建一个大小为 23 的新数组时，我不应该为 LengthOf 取回 23 吗?
When I make a new array of size 23, shouldn't I get 23 back for LengthOf?
WCHAR* str = new WCHAR[23];
str[22] = '';
size_t len = LengthOf(str); // len == 4
为什么len == 4?
UPDATE:我打错了，它是 WCHAR*，而不是 WCHAR**.
UPDATE: I made a typo, it's a WCHAR*, not a WCHAR**.
推荐答案
因为这里的str是指向指针的指针，而不是数组.
Because str here is a pointer to a pointer, not an array.
这是指针和数组之间的细微差别之一:在这种情况下，您的 指针 在堆栈上，指向已分配到其他地方(可能是堆)的 23 个字符的数组.
This is one of the fine differences between pointers and arrays: in this case, your pointer is on the stack, pointing to the array of 23 characters that has been allocated elsewhere (presumably the heap).
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