CODEWITHSUNDEEP
macrosc-preprocessor
Lhse
Lhse

Reputation: 3

C, Find the intermediate value of a define

Given the following defines :

#define foo bar
#define bar 2

#define reg_bar 4

I'm trying to create a macro that given the define foo, find the value of the define reg_bar, 4.

I tried this:

#define foo_bar(value) reg_##value

foo_bar(foo)

But it doesn't work, as it returns reg_foo.

And this 

#define foo_bar(value) reg_##value
#define foo_bar_2(value) foo_bar(value)

foo_bar_2(foo)

But it still doesn't work as it returns reg_2

Is there anyway to do it, only with macro and preprocessor?

Thanks for your help :)

Upvotes: 0

Views: 48

Answers (1)

rici
rici

Reputation: 241791

Sadly, no. There is no such thing as an "intermediate value". A token sequence is either expanded or not; ## suppresses expansion, but there is nothing which suppressed "part of" the expansion.

Upvotes: 0

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