Re: Counting array initializers

Rich Pasco wrote:


You need to quit trying to use the preprocessor for something it was
not designed to be used for. In most cases you just don't need the
preprocessor except to define some macros, perform conditional
compilation based on those macros or predefined macros from the
implementation and include some headers.

What you seem to need to do you can do with templates. The
simplest way is

    // here are your check helpers
    template<bool> struct arraysize;
    template<> struct arraysize<true> { typedef int OK; };
    #define SPLICE2(a, b) a ## b
    #define SPLICE(a, b) SPLICE2(a, b)
    #define CHECK_ARRAY(a) \
      arraysize<sizeof(a)/sizeof(*a) <= maximum_size>::OK \
        SPLICE(OK, __LINE__)()

    // here is your code
    const int maximum_size = 5;
    char const* blah[] = { "abc", "def", "ghi" };
    char const* blahblah[] = { "a", "b", "c", "d", "e", "f" };

    CHECK_ARRAY(blah); // this should compile fine
    CHECK_ARRAY(blahblah); // this should fail

    int main()
    {
    }

You can massage it into giving a decent error message by changing
the actual cause of the failure to compile, by changing the names
of the involved macros/types/functions, etc.

Now, of course the failure is not on the same line as the array
that's too long. But then you can simply fall back onto

   char const* badarray[maximum_size] = { ...

V
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