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Asked: 2026-05-24T18:48:34+00:00

I’m running into this issue. This is not about macro functions, just simple string-value

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I’m running into this issue. This is not about macro functions, just simple string-value macro replacement.

I have two header files

test1.h
#define TEST 123
test2.h
#define TEST 456

Now I have a program included both these two headers, but I want my actually TEST to be 123.
How can I avoid defining TEST as 456?

You might think I’m crazy not to simply change the macro, but the situation is: I have a third-party decoder, which has this macro (defined in test1.h), and there’s another WINAPI macro (defined in test2.h). Both of these files are controlled by others; I should not change either of them.
I don’t need the test2.h at all, but I guess it’s implicitly included by some other WINAPI header.

So, could anyone please tell me how to work around this issue? To overwrite the WINAPI macro with my third-party macro? Or how to nullify the definition from the WINAPI header in my own code? Is there a way to specify which header I don’t want to include.

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1 Answer

  1. Editorial Team

    You can use the #ifdef pre-processor directive to determine if TEST is defined already for your particular case. Or just #undef it first.

    #undef TEST
#define TEST 123

    Put that in your header file where you want TEST to be 123 and not 456. Also, this needs to be before test1.h.

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