Cannot see namespace outside the namespace of a declared class

[Harinezumi]

Hello,

I have a problem with declaring a class in my namespace and using std::string in that class. For example:

#include <string>
 
namespace A {
class myWindow {
public:
   ...
private:
   std::string title;
};
 
} // end of namespace A

The compiler gives an error like A::std::string not defined.
If I put a
using namespace std;
or a
using std::string;
after the include of string header, the compiler gives the error that title has incomplete type (if I remember correctly, but I'm not sure).

Could someone enlighten me about what the problem is?

Thanks in advance,

[weaknessforcats]

string is defined in the std namespace. That makes the fully qualified name std::string. If this string is in your A namespace, it is still std::string.

Your class is A::myWindow since the class declaration is in the A namespace.

[Harinezumi]

string is defined in the std namespace. That makes the fully qualified name std::string. If this string is in your A namespace, it is still std::string.

Your class is A::myWindow since the class declaration is in the A namespace.

Hi,

thanks for the help, I didn't know that you can refer outside of the current namespace with the fully qualified name. I use that now.

However, actually the problem was that myClass was derived from another class (let's call it Base) in the same namespace (A). class Base had an std::list as a member variable, so I #included <list>, but within the namespace A. That caused the problem, because the compiler included stuff for list as part of that namespace (e.g. A::std::list). And then common code for std::string could not be found.

[weaknessforcats]

The <list> should not be included in a namespace of your own unless you intend to restrict it.

It's kinda like: if it hurts to bend your arm that way, then don't do it.