::std

[monarch_dodra]

3: Whenever a name x defined in the standard library is mentioned, the name x is assumed to be fully qualified as ::std::x, unless explicitly described otherwise. For example, if the Effects section for library function F is described as calling library function G, the function ::std::G is meant.

I was reading the standard, and came across this. I noticed that the std namespace was fully qualified to reference the "global" std namespace. While I realize it is probably overkill to do it in an everyday program ("::std::string myString"), I asked myself this question: Can it even serve a use to fully qualify std? I know the standard makes it illegal to put anything inside the std namespace (except for full template sepcializations), so is there a point?

Can you think of a case where writing ::std would be mandatory?

[JohnW@Wessex]

I suppose it may be necessary if someone has created a 'std' namespace within another namespace.

This won't compile without the :: qualifier.

#include <algorithm>

namespace application
{
    namespace std
    {
    }
}

using namespace application;

int main()
{
    int a[10];
    
    ::std::distance(&a[0], &a[10]);
}

[monarch_dodra]

I suppose it may be necessary if someone has created a 'std' namespace within another namespace.

This won't compile without the :: qualifier.

#include <algorithm>

namespace application
{
    namespace std
    {
    }
}

using namespace application;

int main()
{
    int a[10];
    
    ::std::distance(&a[0], &a[10]);
}

I had thought of that, but that would be the only case right? Besides, are you even allowed to do that?

[laserlight]

Besides, are you even allowed to do that?

Yes, you are.

[monarch_dodra]

Thanks for your answers.