11(iii). Unnamed namespace

//Program for illustrate the Unnamed namespace
#include<iostream>
using namespace std;
namespace
{
	int a=19;
	namespace
	{
		int b=20;
		namespace
		{
			int c=30;
			namespace
			{
				int d=40;
			}
		}
	}
}
void display()
{
cout<<"namespace1: "<<a<<endl;
cout<<"namespace2: "<<b<<endl;
cout<<"namespace3: "<<c<<endl;	
cout<<"namespace4: "<<d<<endl;
}
int main()
{
	display();
	return 0;
}

/*   //for better result please remove the /* and 8? and try yourself
#include<iostream>
using namespace std;
namespace
{
	int a=10;
	
}
namespace
{
	int b=20;
}
namespace
{
	int c=40;
}
void display()
{
	cout<<"namespace1: "<<a<<endl;
}
void dsplay()
{
	cout<<"namespace2: "<<b<<endl;
}
void diapl()
{
	cout<<"Namespace3: "<<c<<endl;
}
int main()
{
	display();
	dsplay();
	diapl();
	return 0;
}
*/

//explicit qualification
/* remove this  /* and */ for compile
#include<iostream>
using namespace std;
int i=9;
namespace A
{
	int a=22,b=44,c=55;
	namespace B
	{
		int i=10,j=20,k=30;
	}
}
int  main()
{
cout<<A::a++;
cout<<"\n";
cout<<A::B::i++;
cout<<"\n";
cout<<::i++;  //global	
return 0;
}


//we are invoking the global namespace using scope resolution without preciding qualifier
*/