Can I declare a string in a header file in a definition of a class? [duplicate]

Question

Is it possible to declare a string at all in a header (.h) file, in the definition of a Class?

When I want to set a default int, I do:

 class MyClass
 {
     static const unsigned int kDATA_IMAGE_WIDTH =  1024;

Is there a way to do the same for the string object?

 class MyClass
 {
      static const string kDEFAULT_FILE_EXTENSION = "png"; // fail

I know I can use #define...

 #define kDEFAULT_FILE_EXTENSION "png"

thanks

edit: added that it is in a class definition. updated examples.

Answer 1

From the error message you gave (emphasis mine):

error: invalid in-class initialization of static data member of non-integral type 'const std::string'

You can do this in a header file, but you cannot do so in a class.

That is:

class MyClass
{
    static const std::string invalid = "something";
};

is not valid, but

static const std::string valid = "something else";

is valid.

If you want the static to be a member of the class only, you do this:

//Header
class MyClass
{
    static const std::string valid;
};


//Implementation (.cpp) file

const std::string MyClass::valid = "something else again";

Only static const integral class variables may be initialized using the "= constant" syntax.