如何定义在C界定？ [英] How to define a define in C?

问题描述

是否有可能写一个的#define 定义了一个的#define ？

Is it possible to write a #define that defines a #define?

例如：

#define FID_STRS(x) #x
#define FID_STRE(x) FID_STRS(x)
#define FID_DECL(n, v) static int FIDN_##n = v;static const char *FIDS_##n = FID_STRE(v)

但相反：

#define FID_DECL2(n, v) #define FIDN_##n v \
                               FIDS_##n FID_STRE(v)

FID_DECL 工作正常，但创建两个静态变量。是否有可能使 FID_DECL2 工作，有定义两个定义？

FID_DECL works fine but creates two static variables. Is it possible to make FID_DECL2 work and having define two defines?

推荐答案

没有; preprocessing在单个遍次中执行。如果你想要或需要更先进的行为，可以考虑使用另一种工具来preprocess源，如M4。

No; preprocessing is performed in a single pass. If you want or need more advanced behavior, consider using another tool to preprocess the source, like m4.

此外，＃替换列表中（在的#define FIDN ... 的开始将是解析为＃（stringize）运算符：此运算符的操作数必须是一个名为宏参数，其中定义是没有。

Further, the # in the replacement list (at the beginning of #define FIDN... would be parsed as the # (stringize) operator: the operand of this operator must be a named macro parameter, which define is not.

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