Use `const char thing [] =" foo ";` in your header file?

I want to create a persistent global char array such that

• It can be used in several translation units.
• The length of the array is inferred from the string literal used to initialize it.
• This string literal exists exactly once in my source (and object files if possible).
• If all translation units have a length access time.
• Has no ODR violations when multiple translation units are linked together.

In theory this should be possible by using const char[]

and putting the braking / definition in the header file in such a way that the data / symbol is included in the COMDAT section, but I don't know if the standard (or even any compilers) support this.

ps Suppose any idiom is used will be used for hundreds of thousands of constants in many files.

Edit: The "cleanest" solution I know of gives all points:

template<bool> struct data_ {
  static const char kFoo[];
};

template<> const char data_<true>::kFoo[] = "bar\0other\0stuff\0";
typedef data_<true> data;


#include <stdio.h>

template<typename T, int N>
void Print(T(&var)[N]) { printf("%d %s\n", N, var); }

int main() { Print(data::kFoo); return 0; }

      

        
        
        
      

    

It's still pretty ugly.

OTOH If I just throw out 3b (guaranteed same built-in storage) then this work:

const char kFoo[] = "bar\0other\0stuff\0";

      

        
        
        
      

    

as it has internal linkage by default. A good linker can combine them, but at this point you cannot say anything about the relationship between address / ID equality (i.e., don't pass it to a pointer and use it as an ID). But this is a caveat that is likely to be benign most of the time.