指针之间的区别，以指针数组和指针数组 [英] Difference between pointer to pointer array and pointer array

问题描述

什么是 INT之间的不同** P 和为int * P2 [5] 在第一个字母p是一个指向指针数组，我将在稍后确定！
但P2还指向指针数组!!!!
为int * P2 [5] 相同 P2 INT [5]; 。
因为在这两种情况下，p2为指针！
有什么区别？

解决方案

  INT ** P
 

这是一个指针的指针的 INT 。因此， P 可能指向一个指针或指针数组。反过来 * P 可能指向一个 INT 或数组 INT 。究竟背后是什么 P 在其类型pssed不前$ P $。

 为int * P2 [5]
 

这是一个数组，长度为5，指针为 INT 。在这里， P2 是一个长度为5。关于毫无疑问的数组。但对于 P2 [I] ？他们可能是指向一个 INT ，或指针数组。再次，该信息是不是在类型$ P ​​$ psent

在这个问题你的状态：

  

P2 是一个指针。

这说法是不正确的。 P2 是一个数组，而不是一个指针。在某些情况下， P2 可能的衰减的一个指针，但它本身并不是一个指针。

请注意，如果你开始与变量 P2 ，那么你可以把它分配给 P 这样的：

  P = P2;
 

这是一个数组， P2 ，腐烂的指针。在这一点上，你知道， P 指向指针数组来 INT 。

不过，如果你有一些 P 类型 INT ** 那么你不知道 p 指向数组。它可能不是。换句话说，指针的类型不完全描述它所指向

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您似乎得到相当困惑的一个数组和指针的区别。它们是不相同的。阵列不是指针。阵列可以衰减到一个指针。一个指针可以在一个阵列点。

也许关键区别在于一个数组总是以相同的变量。另一方面，一个指针可以由在不同的变量的点。另一个明显的区别是，一个数组变量定义存储。另一方面，一个限定一指针变量没有。必须始终指针赋值给其他对象的地址。

What is the different between int **p and int *p2[5] in the first case p is a pointer to pointers to an array that i will define later!, but p2 also point to array of pointers!!!!. int *p2[5] is the same as int p2[5];. Because in both cases p2 is pointer !. what is the difference?

解决方案

int **p

This is a pointer to pointer to int. So p could point to a single pointer, or an array of pointers. In turn *p could point to a single int, or an array of int. Exactly what is behind p is not expressed in its type.

int *p2[5]

This is an array, of length 5, of pointer to int. Here, p2 is an array of length 5. No doubt about that. But what about p2[i]? They could be pointers to a single int, or pointers to an array. Again, the information is not present in the type.

In the question you state:

p2 is a pointer.

That statement is not correct. p2 is an array, and not a pointer. In certain contexts, p2 may decay to a pointer, but it is not in itself a pointer.

Note that if you start with the variable p2, then you can assign it to p like this:

p = p2;

This is an array, p2, decaying to a pointer. At this point you know that p points to an array of pointer to int.

However, if all you have is some p of type int** then you do not know the p points to an array. It might not. In other words, the type of a pointer does not fully describe what it points to.

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You seem to be getting quite confused about the difference between an array and a pointer. They are not the same. An array is not a pointer. An array can decay to a pointer. A pointer can point at an array.

Perhaps the key difference is that an array always refers to the same variables. On the other hand, a pointer can be made to point at different variables. Another obvious difference is that an array variable defines storage. On the other hand, a defining a pointer variable does not. You must always assign the pointer to the address of some other object.

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