C Preprocessor precedence

Question

I have the following problem:

extern void func_name(const char *f); #define EXPECT(f) func_name(#f) #define foo bar void main() { EXPECT(foo); }

So, the

EXPECT(foo);

will be actually evaluated to

func_name("foo");

What I actually need is to convert 'foo' to 'bar', i.e. the code to become

func_name("bar");

So I kind of want to do this:

#define "foo" "bar"

But this does not work, because macro names must be identifiers. I also tried to find a way to change the preprocessor precedence, so my macro will be replaced first, but didn't find a way.

The perfect solution will not change main() at all.

I just ran into this. stackoverflow.com/questions/25331999/macro-meta-programming — IdeaHat
– IdeaHat, Commented Aug 20, 2014 at 20:57
If your textbook tells you that void main() is correct, its author has lied to you. Get a better book. The correct definition is int main(void). — Keith Thompson
– Keith Thompson, Commented Aug 20, 2014 at 21:01
possible duplicate of C Preprocessor, Stringify the result of a macro — Alex Celeste
– Alex Celeste, Commented Aug 20, 2014 at 22:38

BLUEPIXY · Accepted Answer · 2014-08-20 20:57:07Z

4

#define S(x) #x #define EXPECT(f) func_name(S(f))

answered Aug 20, 2014 at 20:57

BLUEPIXY

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