C 中指针的 const 用法 [英] const usage with pointers in C

问题描述

我正在学习 C 并且有一个关于 const 使用指针的问题.我理解以下代码:

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 char 类型的指针，const 修饰符意味着存储在 someArray 中的值不能改变.但是，以下是什么意思?

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

这是指定参数的替代方法，该参数是指向名为array"的数组的字符指针，该数组是 const 并且无法修改?

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，这个组合是什么意思:

Lastly, what does this combination mean:

const char * const s2

作为参考，这些取自第 7 章的 Deitel C 编程书籍，所有这些都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

const char* 就像你说的，是一个指向 char 的指针，在那里你不能改变 char 的值(至少不是通过指针(没有将常量丢弃)).

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 是一个指向字符的指针，您可以在其中更改字符，但不能使指针指向不同的字符.

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.

const char* const 是一个指向常量 char 的常量指针，即你不能改变指针指向的位置，也不能改变指针的值.

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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