How to modify the value of a preprocessor based on the value returned by a command or script?

Question

On visual Studio 2022 how to have a preprocessor value defined based on the result returned by a script?

What i tried:

Solution Explorer > Properties > Build Events > Pre-Build Event > Command Line > "python script.py > output.txt"

But im not figuring how to use the output as the value for the preprocessor TEST

#include <iostream>
int main(int argc, char *argv[])
{
#ifdef TEST
    std::cout << "OK";
#else
    std::cout << "FAILED";
 #endif
}

Answer 1

Hi, @Leo Purktz

As Viorel suggested, you can define Marco via script and header file.

#include <iostream>
#include"myheader.h"
int main(int argc, char* argv[])
{
#ifdef TEST
    std::cout << "OK";
#else
    std::cout << "FAILED";
#endif
}

Pre-build event

if exist output.txt (
    echo #define TEST 1 > myheader.h
) else (
    echo. > myheader.h
)

Best regards,

Minxin Yu

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