using namespace std;

How do I turn it off, i.e. that I am not using namespace std anymore?

/Esa

There is no way.  Don't use using namespace std; - it is evil.  Name
specifically those functions/types/classes/etc you want to use.  Also
try to name them with using _inside_ you function bodies.  Outside use
std:: (like for return values).  Don't pollute the global namespace if
you don't have to.

A

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

or (b) name them in 'using' declarations:

    using std::cout;
    using std::endl;

--
Jon Bell <jtb...@presby.edu>                        Presbyterian College
Dept. of Physics and Computer Science        Clinton, South Carolina USA

Impossible, but there is a workaround and advice: *never* use 'using
namespace' (IMHO 'using' shouldn't exist at all).

Radoslav Getov

using namespace std;

at the beginning of each source file that uses features from the
standard library. Of course, you might have problems if you have classes
in other namespaces with the same name like standard library classes,
but do people really do that?

Regards,
Thomas Kunert

I would very much like to be able to write (particularly in header
files) using namespace xyz at the beginning and ~using namespace xyz at
the end. But I would also like to be able to write:

using namespace xyz;
~using xyz::feature;

Now my question is 'how much more complicated does this make compiler
writing?

Francis Glassborow      ACCU
64 Southfield Rd
Oxford OX4 1PA          +44(0)1865 246490
All opinions are mine and do not represent those of any organisation

I suggets you do write it only to function bodies etc. where is it
"scoped".  In the declarations take the time to fully qualify your
references, like:

std::string Class::cnvStr( const std::string & s, const std::string
&cnvlist) {
  using std::string;
  using std::whatever;
  // ...

But I agree that you never should put
        using namespace std;
in global scope, or probably anywhere. It is too big a hammer,
introducing names you probably do not expect.

Unfortunately, many example programs in many textbooks
employ such a using-declaration. I don't know why. I would
steer clear of such books, as they probably contain other
bad advice.

Even in a toy program it is a simple matter to add a using-
directive for just the names you intend to use:

#include <iostream>
using std::cout;
using std::endl;

int main()
{
    cout << "Hello, world!" << endl;

---
Steve Clamage, stephen.clam...@sun.com

--
Jon Bell <jtb...@presby.edu>                        Presbyterian College
Dept. of Physics and Computer Science        Clinton, South Carolina USA

I do agree that "using namespace blah;" is bad practice *in most cases* and
should be avoided.