5. The std namespace

• All C++ standard library stuff is defined inside the std namespace.

• Saying

  
      #include <iostream>
  
      using namespace std;
  
  

  means that C++ will give you everything from std without requiring std:: qualification.

  For example, cout is really the std::cout:

  
      #include <iostream>
      int main()
      {
          using namespace std;
          cout << "hello";
          return 0;
      }
  
  

• Other than I/O, what else is there in std namespace?

  • Lots, and all organized using C++ templates!