对于非数组对象类型，尾数指针可以吗？
Is one-past-end pointer OK for non-array object types?
这是有效的 C++ 吗？
int main()
{
int i = 0;
int* pi = &i;
++pi;
}
我知道数组类型允许使用尾数指针，但在这种情况下我不确定。该代码在技术上是否具有未定义的行为？
是的，没关系。它是任何指针类型都可以持有的四类值之一。
[basic.compound] (emphasis mine)
3 Every value of pointer type is one of the following:
- a pointer to an object or function (the pointer is said to point to the object or function), or
- a pointer past the end of an object ([expr.add]), or
- the null pointer value ([conv.ptr]) for that type, or
- an invalid pointer value.
A value of a pointer type that is a pointer to or past the end of an
object represents the address of the first byte in memory
([intro.memory]) occupied by the object or the first byte in memory
after the end of the storage occupied by the object, respectively. [
Note: A pointer past the end of an object ([expr.add]) is not
considered to point to an unrelated object of the object's type that
might be located at that address. A pointer value becomes invalid when
the storage it denotes reaches the end of its storage duration; see
[basic.stc]. — end note ] For purposes of pointer arithmetic
([expr.add]) and comparison ([expr.rel], [expr.eq]), a pointer past
the end of the last element of an array x of n elements is considered
to be equivalent to a pointer to a hypothetical array element n of x
and an object of type T that is not an array element is considered to
belong to an array with one element of type T.
如你所见，这里也提到了数组类型，其假设的对象在末尾。正如 footnote in [expr.add] 所解释的那样，获得尾后一个指针的算法 意味着 也有效：
As specified in [basic.compound], an object that is not an array element is considered to belong to a single-element array for this purpose and a pointer past the last element of an array of n elements is considered to be equivalent to a pointer to a hypothetical array element n for this purpose.
这是有效的 C++ 吗？
int main()
{
int i = 0;
int* pi = &i;
++pi;
}
我知道数组类型允许使用尾数指针，但在这种情况下我不确定。该代码在技术上是否具有未定义的行为？
是的，没关系。它是任何指针类型都可以持有的四类值之一。
[basic.compound] (emphasis mine)
3 Every value of pointer type is one of the following:
- a pointer to an object or function (the pointer is said to point to the object or function), or
- a pointer past the end of an object ([expr.add]), or
- the null pointer value ([conv.ptr]) for that type, or
- an invalid pointer value.
A value of a pointer type that is a pointer to or past the end of an object represents the address of the first byte in memory ([intro.memory]) occupied by the object or the first byte in memory after the end of the storage occupied by the object, respectively. [ Note: A pointer past the end of an object ([expr.add]) is not considered to point to an unrelated object of the object's type that might be located at that address. A pointer value becomes invalid when the storage it denotes reaches the end of its storage duration; see [basic.stc]. — end note ] For purposes of pointer arithmetic ([expr.add]) and comparison ([expr.rel], [expr.eq]), a pointer past the end of the last element of an array x of n elements is considered to be equivalent to a pointer to a hypothetical array element n of x and an object of type T that is not an array element is considered to belong to an array with one element of type T.
如你所见，这里也提到了数组类型，其假设的对象在末尾。正如 footnote in [expr.add] 所解释的那样，获得尾后一个指针的算法 意味着 也有效：
As specified in [basic.compound], an object that is not an array element is considered to belong to a single-element array for this purpose and a pointer past the last element of an array of n elements is considered to be equivalent to a pointer to a hypothetical array element n for this purpose.