static const & literal

[Gener4tor]

Hi...I have a question concerning const/literal-functions and members

c++:
struct StyleConstants
{
static const CString TestConst="UniqueStringWhichShouldBeOnlyWrittenOnceInTheCode";
}

cli:
public ref class StyleConstNet
{
literal String^ TestConst=StyleConstants::TestConst;
}

but the code retrifes an Error:
error C3887: 'StyleConstNet::TestConst: the initializer for a literal data member must be a constant expression

The main problem is: I have to use StyleConstNet.TestConst like this:
case StyleConstNet.TestConst:
inside an switch-statement.

Is there any solution to this without ?

[Gener4tor]

Is there any solution to this without have to write the string twice in the Code?

[Alex F]

What about good old #define directive?

[Eri523]

First, I wonder how you got this to compile in the first place (aside from the missing semicolon):

c++:
struct StyleConstants
{
static const CString TestConst="UniqueStringWhichShouldBeOnlyWrittenOnceInTheCode";
}

When I try this (with std::string in place of the CString though, because I don't have MFC here), I get an error C2864. It only works for me with TestConst at file scope (however, you may put it into a namespace).

error C3887: 'StyleConstNet::TestConst: the initializer for a literal data member must be a constant expression

Unfortunately this is the plain truth. The initializer for a literal member must be a compile-time constant. The CString, however, is an object that needs to be constructed at runtime, so it doesn't work that way. (And I'm not even sure you actually can simply assign a CString to a .NET System::String ^ at all, even away from the context of initialization.)

If you really don't want to write the constant twice in your code (which I can understand because it complicates maintainance), I think the adequate solution here is a really trivial one, #define the string literal as s macro:

#define TESTCONST "UniqueStringWhichShouldBeOnlyWrittenOnceInTheCode"

// c++:
struct StyleConstants
{
  static const CString TestConst=TESTCONST;
}

// cli:
public ref class StyleConstNet
{
  literal String^ TestConst=TESTCONST;
}

Please use code tags when posting code.

Ah, and... welcome to CodeGuru!

EDIT: Alex F was quicker yet again...

[Alex F]

Alex F was quicker yet again...

Maybe because my answer was a bit shorter

[Eri523]

Maybe because my answer was a bit shorter

Certainly. You know I always tend to those elaborate (wordy?) replies...