Exporting constants from a DLL

I'm working with VC9 on Windows.

I have a library (lets call it libfoo) which is made of the following files ("include guards" and "#include" directives omited for clarity's sake):

// foo.hpp

class Foo
{
  public:
    static const std::string SOME_CONST;
};

And:

// foo.cpp

#include "foo.hpp"

const std::string Foo::SOME_CONST = "hello";

Foo::SOME_CONST is exported using a .def file.

The library compiles fine: a libfoo.lib file and a libfoo.dll file are generated.

I used this library in a sample program, like:

// main.cpp

#include <foo.hpp>

int main()
{
  std::cout << Foo::SOME_CONST << std::endl; // std::bad_alloc here

  return EXIT_SUCCESS;
}

A std::bad_alloc is thrown whenever I attempt to use F开发者_JAVA技巧oo::SOME_CONST.

This only happens if I link dynamically to libfoo. Linking statically results in a perfectly working program.

What could possibly be going on here ? Is it legal to export a std::string constant that way ?

Check if dll actually does dynamic initialization, because it might not, standard has no requirements for dynamic libraries. Wrapping globals in static functions can be the solution.

Use __declspec(dllexport) and __declspec(dllimport). Stop worrying about .def files and all of that rubbish- let the compiler do the work.

Are the library and the main application linking to the same version of the standard library and/or CRT and/or MFC, with exactly the same settings? I've seen allocation issues when using different versions of the CRT, and also fought bugs caused by different iterator debugging settings between a library and its including application.