Question

I have a 2-dimensional array of pointer to char and initialising it in a header file.
The problem is this: it doesn’t complain getting assigned a const char[] but does not like me assigning const char* (as shown in the code). It gives me an error “initializer element is not constant”.

const char lang[8] = "English";

const char * langPtr = "English 1";

const char * optionPtr[3][10] = {

    {lang, 0, 0, 0, 0, 0, 0, 0, 0, 0, },

    {langPtr, 0, ...},    

    {...}

};

I thought lang and langPtr are both pointing at the beginning of a string so should be able to do this. I want to use a pointer to initialise the 2D array. Is there anyway of doing this globally?

Answer 1

In C, elements in initialisers for static objects must be “constant expressions” (all global objects are static).

The address of a static object is an “address constant”, which is a kind of “constant expression” – that’s why lang works. The value of a variable – even a const variable (though note that langPtr itself is not const) – is not a “constant expression”, which is why langPtr does not work.

Note that this is different in C++, where const qualified variables are genuine constants.