Thread: using namespace std;

hey guys, can someone explain the difference of declaring namespace right below the library

Code:

#include <iostream>
using namespace std;

and using the std:: in the code it self?

Code:

std::cout << "Hello, World!" << std::endl;

is this compiler specific, and is there a standard? I have two books, "Absolute C++" by Savitch whitch teaches the decleration of 'using namespace std;' and "Accelerated C++" by Koenig and Moo whitch starts of with std::

thankx,

axon

----edit----
I use VC++ 6.0, and both ways work, but the authors of accelerated c++ say that things such as

Code:

using std::vector
vector<double>::size_type n = 0;

does not work, and displays and error message