文件范围内可变修改的数组 [英] Variably modified array at file scope

问题描述

我想在我的 Objective-C 实现文件中创建一个常量静态数组，类似于我的.m"文件的顶层:

I want to create a constant static array to be used throughout my Objective-C implementation file similar to something like this at the top level of my ".m" file:

static const int NUM_TYPES = 4;
static int types[NUM_TYPES] = { 
  1,
  2, 
  3, 
  4 };

我计划稍后在文件中使用 NUM_TYPES，因此我想将其放入一个变量中.

I plan on using NUM_TYPES later on in the file so I wanted to put it in a variable.

但是，当我这样做时，我收到错误

However, when I do this, I get the error

在文件范围内可变修改的‘类型’"

"Variably modified 'types' at file scope"

我认为这可能与数组大小是一个变量有关(当我在那里放置一个整数文字时，我没有收到此消息，例如 static int types[4]).

I gather that this may have something to do with the array size being a variable (I don't get this message when I put an integer literal there, like static int types[4]).

我想解决这个问题，但也许我做错了……我在这里有两个目标:

I want to fix this, but maybe I am going about it all wrong...I have 2 goals here:

1. 拥有一个可在整个文件中访问的数组
2. 将 NUM_TYPES 封装到一个变量中，这样我的文件中的不同位置就不会散布相同的文字

1. To have an array which is accessible throughout the file
2. To encapsulate NUM_TYPES into a variable so I don't have the same literal scattered about different places in my file

有什么建议吗?

在 C 常见问题解答中找到了这个:http://c-faq.com/ansi/constasconst.html

Found this in the C Faq: http://c-faq.com/ansi/constasconst.html

推荐答案

出现这个警告的原因是 c 中的常量并不意味着常量.它的意思是只读".因此该值存储在内存地址中，并且可能会被机器代码更改.

The reason for this warning is that const in c doesn't mean constant. It means "read only". So the value is stored at a memory address and could potentially be changed by machine code.

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