c++ - 分配函数和返回指针

Question

我不理解合适的指针对齐概念:

There are no constraints on the contents of the allocated storage on return from the allocation function. The order, contiguity, and initial value of storage allocated by successive calls to an allocation function are unspecified. The pointer returned shall be suitably aligned so that it can be converted to a pointer of any complete object type with a fundamental alignment requirement (3.11) and then used to access the object or array in the storage allocated (until the storage is explicitly deallocated by a call to a corresponding deallocation function).

sec.3.11 中没有合适对齐的定义。你解释一下应该是什么意思？

Answer 1

这意味着对于具有基本对齐的任何完整对象类型，应该可以将返回的指针转换为指向该对象类型的指针，同时遵守该对象类型的对齐要求。

在实践中，由于对齐是 2 的幂，这意味着分配函数需要返回一个与 alignof(std::max_align_t) 对齐的指针。

“合适的对齐方式”没有单独的定义；在本段中和其他地方一样，“适本地”仅表示程序需要满足该段其余部分才能满足的要求。