我真正需要的可能是一个静态大小的多维数组
>具有“适当的”价值语义,并且
>连续存储在内存中.
看起来,与C风格的数组不同,std :: array的std :: array不能保证具有完全紧凑的内存,因为std :: array可能包含填充.
如果我使用像std :: array< int [2] [2],2>？这样的问题可能会有什么问题？也许这是一个太模糊的问题,但很难弄清楚为什么我不舒服,有些怀疑使用它为我的目的.
解决方法
容器must be Erasable from the container type的value_type,其中Erasable在[container.requirements.general] paragraph 15中定义：
Given an allocator type
Aand given a container typeXhaving avalue_typeidentical toTand anallocator_typeidentical toallocator_traits<A>::rebind_alloc<T>and given an lvaluemof typeA,a pointerpof typeT*,an expressionvof type (possiblyconst)T,and an rvaluervof typeT,the following terms are defined. IfXis not allocator-aware,the terms below are defined as if A wereallocator<T>— no allocator object needs to be created and user specializations ofallocator<T>are not instantiated:
…
Tis Erasable fromXmeans that the following expression is well-formed:
allocator_traits<A>::destroy(m,p)
因为std :: array不支持分配器,所以我们需要检查是否正好形成了allocator_traits< allocator< int [2] [2]>> :: destroy(m,p).
由于std::allocator没有成员函数destroy(在C 17中弃用),std::allocator_traits::destroy将直接调用int [2] [2]的(伪)析构函数.这is ill-formed因为int [2] [2]不是scalar type.
