常量的使用与C指针 [英] const usage with pointers in C

问题描述

我要在C和有关于使用指针常量使用的问题。我了解以下code：

I am going over C and have a question regarding const usage with pointers. I understand the following code:

const char *someArray

这是定义一个指向类型char和在常量修改意味着一个指针存储在的someArray 不能改变。然而，什么是下面的意思吗？

This is defining a pointer that points to types of char and the const modifier means that the values stored in someArray cannot be changed. However, what does the following mean?

char * const array

这是指定一个参数，该参数是一个字符指针到名为阵的数组是的另一种方式常量，不能进行修改？

Is this an alternate way of specifying a parameter that is a char pointer to an array named "array" that is const and cannot be modified?

最后，这是什么意思的组合：

Lastly, what does this combination mean:

const char * const s2

有关的参考，这些是从的Deitel C语言编程的书采取的第7章，所有这些被用作传递给函数的参数。

For reference, these are taken from the Deitel C programming book in Chapter 7 and all of these are used as parameters passed to functions.

推荐答案

为const char * 是，如你所说，一个指向一个char，在那里你可以不改变字符的值（至少不是通过指针（没有铸造常量性远））。

const char* is, as you said, a pointer to a char, where you can't change the value of the char (at least not through the pointer (without casting the constness away)).

char * const的是指向一个char，在那里你可以改变字符，但你不能使指针指向一个不同的字符。

char* const is a pointer to a char, where you can change the char, but you can't make the pointer point to a different char.

为const char * const的是一个常量指针，以一个恒定的字符，即可以改变既不当指针指​​向，也不指针对象的值。

const char* const is a constant pointer to a constant char, i.e. you can change neither where the pointer points nor the value of the pointee.

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