我可以使用指针访问多维数组吗? [英] Can I access multidimensional array using a pointer?

问题描述

来自 this 参考，在 C 中似乎以下行为未定义.

From this reference, In C it seems the following behavior is undefined.

int my_array[100][50];
int *p = my_array[0];
p[50]; // UB

C++03 或 C++11 中是否有参考文献证实了这一点?

Is there a reference in C++03 or C++11 which confirms this?

推荐答案

在 + 运算符的描述中是.您不能在 C 中取消引用该指针，因为它超过了第一个子数组的结束指针.在 C++ 中，这目前是合法的，因为指针 points 指向一个有效的整数(指向关系的点在第 3 节中的某处定义).然而，在这两个标准中，添加超过 50 个会产生未定义的行为.

Yes in the description of the + operator. You may not dereference that pointer in C because it is a past the end pointer for the first subarray. In C++ this currently is legal because the pointer points to a valid integer (the points to relation is defined somewhere in clause 3). However in both standards adding more than 50 yields undefined behavior.

最近向 C++ 委员会发送了一份 DR，内容涉及取消引用此类凭空有效"指针可能会取消引用的规则，因此我不会依赖该规则.

A DR was recently sent to the c++ committee about the rule that dereferencing such "valid out of thin air" pointers may be dereferenced, so i would not rely on that.

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