use of namespace

[Umar Dafedar]

for what purpose we use
using namespace std;

[zb0S216C]

That line of code isn't correct. It should be using namespace std. The line you posted, is a preprocessor directive, not a statement.

using namespace std tells the compiler that you will be using the entire standard namespace. This makes all definitions in the standard namespace public, and available to use.

_Wazzak

[Breadman]

There's alot of members in the std namespace. For example cout. So without that line you would simply need to say std::cout.

[Aikon]

C++ got a proteccion for the colisions with names, for example a funcion max() its so current and for this reason let you to define coleccions of names.

When you use this line using namespace std; you are loading all the collecion on std, and then you dont need to do std::cout <<.

This is dungerous becouse if you define a funcion with the name cout you can't have the certaing your program use your funcion, then you could do this:

namespace myCout{
        class cout;
}

And then you can call him: myCout::cout ......;