如何连接，评估和字符串化宏? [英] How to concatenate, evaluate and stringify macros?

问题描述

我正在尝试对宏串联的替换(评估)进行字符串化.例如:

I am trying to stringify the substitution (evaluation) of a macro concatenation. For example:

#include <stdio.h>

#define FOO_ONE 12
#define FOO_TWO 34
#define BAR_ONE 56
#define BAR_TWO 78

#define MAKE_MAC(mac) // ... what to do here?

void main(int argc, char *argv[])
{
    printf("FOO: " MAKE_MAC(FOO) "\n");
    printf("BAR: " MAKE_MAC(BAR) "\n");
}

我正在寻找的结果是:

FOO: 1234
BAR: 5678

我尝试了几种形式，我认为最好的尝试是这样:

I tried a few forms, I think the best attempt is this:

#define STRINGIFY(mac) #mac
#define CONCAT(mac1, mac2) STRINGIFY(mac1 ## mac2)
#define MAKE_MAC(mac) CONCAT(mac, _ONE) CONCAT(mac, _TWO)

但是，这只让我走了这么远:

But, it only gets me this far:

FOO: FOO_ONEFOO_TWO
BAR: BAR_ONEBAR_TWO

那么，如何在字符串化之前添加额外的评估结果级联宏的步骤?

So, how can I add the extra step of evaluation of the resulting concatenated macro, before it gets stringified?

推荐答案

尝试一下:

#include <stdio.h>

#define FOO_ONE 12
#define FOO_TWO 34
#define BAR_ONE 56
#define BAR_TWO 78

#define STRINGIFY(arg) #arg
#define CONCAT(arg1, arg2) STRINGIFY(arg1) STRINGIFY(arg2)

#define MAC(arg) CONCAT(arg##_ONE, arg##_TWO)

int main(){

    printf("FOO: " MAC(FOO) "\n");
    printf("BAR: " MAC(BAR) "\n");

    return 0;
}

我的输出:

FOO: 1234
BAR: 5678

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