Question

对于我正在从事的项目，我需要一个静态初始化的，不可变的全局数组，特别是一个数组，而不是enum。据我所知，最好的方法是使用extern const数组。但是，当我尝试初始化并声明任何数组foo时，会出现两个不同但显然相关的编译器错误：

error: conflicting types for `foo'
error: invalid initializer

在我的.c文件的外部范围中的每次初始化都重复这些操作。这些错误中的前一个总是紧随其后的注释读为“ previous declaration of `foo' was here”，并指向头文件中数组的声明。

在下面的示例中...

#ifndef __MWE__
#define __MWE__

extern const int foo[8];

#endif /* MWE */

#include "mwe.h"
const int foo[0] = 0;
const int foo[1] = 42;
const int foo[2] = 69;
const int foo[3] = 420;
const int foo[4] = 9001;


int main(int argc,char**argv){return 0;}

...我遇到以下错误...

mwe.c:3:11: error: conflicting types for ‘foo’
 const int foo[0] = 0;
           ^~~
In file included from mwe.c:1:0:
mwe.h:4:18: note: previous declaration of ‘foo’ was here
 extern const int foo[5];
                  ^~~
mwe.c:3:20: error: invalid initializer
 const int foo[0] = 0;
                    ^
mwe.c:4:11: error: conflicting types for ‘foo’
 const int foo[1] = 42;
           ^~~
In file included from mwe.c:1:0:
mwe.h:4:18: note: previous declaration of ‘foo’ was here
 extern const int foo[5];
                  ^~~
mwe.c:4:20: error: invalid initializer
 const int foo[1] = 42;
                    ^~
mwe.c:5:11: error: conflicting types for ‘foo’
 const int foo[2] = 69;
           ^~~
In file included from mwe.c:1:0:
mwe.h:4:18: note: previous declaration of ‘foo’ was here
 extern const int foo[5];
                  ^~~
mwe.c:5:20: error: invalid initializer
 const int foo[2] = 69;
                    ^~
mwe.c:6:11: error: conflicting types for ‘foo’
 const int foo[3] = 420;
           ^~~
In file included from mwe.c:1:0:
mwe.h:4:18: note: previous declaration of ‘foo’ was here
 extern const int foo[5];
                  ^~~
mwe.c:6:20: error: invalid initializer
 const int foo[3] = 420;
                    ^~~
mwe.c:7:11: error: conflicting types for ‘foo’
 const int foo[4] = 9001;
           ^~~
In file included from mwe.c:1:0:
mwe.h:4:18: note: previous declaration of ‘foo’ was here
 extern const int foo[5];
                  ^~~
mwe.c:7:20: error: invalid initializer
 const int foo[4] = 9001;

声明和初始化extern const数组的正确方法是什么，这种方法无效是什么？类型冲突在哪里？为什么整数文字是整数数组元素的无效初始化器？

Answer 1

每个：

const int foo[0] = 0;
const int foo[1] = 42;
const int foo[2] = 69;
const int foo[3] = 420;
const int foo[4] = 9001;

分别命名为foo的数组变量，每个变量的大小都不同。您还尝试使用单个值初始化这些数组。这就是为什么您会得到错误。

如果要初始化数组，请执行以下操作：

const int foo[5] = { 0, 42, 69, 420, 9001 };

如果您需要基于枚举值初始化特定的索引，则可以使用指定的初始化程序来完成此操作：

enum {
    E1, E2, E3, E4, E5
};
const int foo[5] = { 
    [E1] = 0, 
    [E2] = 42, 
    [E3] = 69, 
    [E4] = 420, 
    [E5] = 9001 
};

extern const数组声明/初始化错误（无效的初始化器/冲突类型）

1 个答案: