Thanks that puts me on the way to solve it! There was a C++ mistake left, I ended up with this 
use Inline 'CPP' => << 'END';
int countGC(char * _gcString) {
        std::string gcString(_gcString);
        int res(0);
        for (int i = 0; i < gcString.length(); i++) { if (gcString[i] 
+== 'C' || gcString[i] == 'G') { res++; } }
        return res;
}
END

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In reply to Re^2: Inline CPP undefined subroutine by Alessandro
in thread Inline CPP undefined subroutine by Alessandro

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