Introducing the Game Over 2.0 Program
The Game Over 2.0 program produces the exact results of the original Game Over program, illustrated in Figure 1.2. But there’s a difference in the way elements from the std namespace are accessed.
Working with the std Namespace
Because it’s so common to use elements from the std namespace, I’ll show you two different methods for directly accessing these elements. This will save you the effort of using the std:: prefix all the time.
Employing a using Directive
The program starts in the same way. I use two opening comments and then include iostream for output. But next, I have a new type of statement.
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using namespace std;
This using directive gives me direct access to elements of the std namespace. Again, if a namespace is like an area code, then this line says that all of the elements in the std namespace should be like local phone numbers to me now. That is, I don’t have to use their area code (the std:: prefix) to access them.
I can use cout and endl, without any kind of prefix. This might not seem like a big deal to you now, but when you have dozens or even hundreds of references to these objects, you’ll thank me.
Code
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// Game Over 2.0
// Demostrates a using directive
#include <iostream>
using namespace std;
int main()
{
cout << "Game Over!" << endl;
return 0;
}
Output
Game Over!