on Wed Dec 12 2012, Gottlob Frege <gottlobfrege-AT-gmail.com> wrote:
On Wed, Dec 12, 2012 at 10:49 AM, Rob Stewart <robertstewart@comcast.net>wrote:
std::string does not have a 'null' state.
It's the state represented by empty().
I am not sure it is so certainly accepted by all.
It is the logical interpretation. It indicates whether the string is non-empty. I don't see any other generally useful interpretation, do you?
Qt's QString has both empty() and isNull() and they are not always the same. Basically empty() is a zero-byte string, but null is a never-been-set-or-allocated string.
That's dumb, though.
ie
QString name = database.get("Name");
name.empty() == true means the Name field was empty name.isNull() == true means the Name field doesn't exist in the database.
Somewhat like optional<string>.
I am NOT saying whether this is a good thing. Just a widely known example of interpretation.
I AM saying it's a bad thing! :-) -- Dave Abrahams BoostPro Computing Software Development Training http://www.boostpro.com Clang/LLVM/EDG Compilers C++ Boost