在带引号的字符串中展开宏 [英] Expand macros inside quoted string

问题描述

可能重复:
C 宏创建字符串

我有一个函数，它接受一个 char* 类型的参数，例如 f("string");
如果字符串参数是在函数调用中动态定义的，如何在字符串体中展开宏?

I have a function which accepts one argument of type char*, like f("string");
If the string argument is defined by-the-fly in the function call, how can macros be expanded within the string body?

例如:

#define COLOR #00ff00
f("abc COLOR");

相当于

f("abc #00ff00");

但是不执行扩展，函数接收字面意思是abc COLOR.

but instead the expansion is not performed, and the function receives literally abc COLOR.

特别是，我需要将宏完全扩展为 "#00ff00"，以便将这个带引号的标记与传递给 f() 的字符串参数的其余部分连接起来，包括引号；也就是说，预处理器必须完成他的工作，并欢迎编译器将代码从 f("abc COLOR"); 转换为 f("abc "#00ff00"");

In particular, I need to expand the macro to exactly "#00ff00", so that this quoted token is concatenated with the rest of the string argument passed to f(), quotes included; that is, the preprocessor has to finish his job and welcome the compiler transforming the code from f("abc COLOR"); to f("abc "#00ff00"");

推荐答案

不能在字符串中展开宏，但是可以写

You can't expand macros in strings, but you can write

#define COLOR "#00ff00"

f("abc "COLOR);

请记住，这种连接是由 C 预处理器完成的，它只是连接纯字符串的功能，而不是变量等.

Remember that this concatenation is done by the C preprocessor, and is only a feature to concatenate plain strings, not variables or so.

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