编译错误C2099：初始化不是一个常数 [英] compile error C2099: initializer is not a constant

问题描述

以下code编译习惯：

The following code wont compile:

const int a = 0;

struct Test
{
    int b;
};

static const struct Test test = 
{
    a
};

它是一个减少的例子是什么我真的想做，但我究竟做错了什么？

Its a cut down example of what I am really trying to do, but what am I doing wrong?

推荐答案

在C89 / 90版本的C语言的所有集合初始化器必须包含的常量的唯一。在C语言术语不变 INT 的的 的类型是文​​字值，如 10 ， 20U ，为0x1 等枚举成员也是常数。 const int的类型的变量的不的C语言常量不能使用 const int的合计初始化变量。 （由于这个原因，在C语言中，当你需要声明一个命名常量，你应该使用的#define 或枚举，而不是常量预选赛。）

In C89/90 version of C language all aggregate initializers must consist of constants only. In C language terminology a constant of int type is a literal value, like 10, 20u, 0x1 etc. Enum members are also constants. Variables of const int type are not constants in C. You can't use a const int variable in aggregate initializer. (For this reason, in C language, when you need to declare a named constant you should use either #define or enum, but not const qualifier.)

在C99这一要求的骨料初始化很轻松。它现在确定在本地对象的集合体初始化使用非常数。然而，对于静态物体（如你的例子）的要求仍然有效。因此，即使在C99 you'l'必须要么使用

In C99 this requirement for aggregate initializers was relaxed. It is now OK to use non-constants in aggregate initializers of local objects. However, for static objects (as in your example) the requirement still holds. So, even in C99 you'l' have to either use

#define a 0

或使用命名为@R建议枚举常量..的答案。

or use a named enum constant as suggested in @R..'s answer.

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