what does this actually do??

using namespace std;

I have no idea what the importance of the above is.

Thanks

don't know for sure either... but someone [i think davidp] told me that it was for correct function recognition when functions have preceding underscores...

the std namespace is the namespace which the entire Standard c++ libarary is declared. So when you use namespace std you simplify access to the standard library. I also herd it deals with clashes between old and new header files.

A namespace is a piece of code that is encapsulated within a pair of brackets, just like any other class.

Example:

namespace a
{
int AAA;
};

namespace b
{
int BFunc( int x )
{
return x;
}
}

int main()
{
AAA = 5; // error: unknown identifier AAA
a::AAA = 5; // ok
BFunc( AAA ); // error: unknown identifiers: AAA and BFunc
b::BFunc( a::AAA ); // ok

return 0;
}

The using directive means you try to use this prefix automatically:

using namespace a;

int main()
{
AAA = 5; // ok, a:: added automatically
a::AAA = 5; // ok
BFunc( AAA ); // error: unknown identifier BFunc
b::BFunc( a::AAA ); // ok

return 0;
}

All functions in the C++ headers belong to namespace std.
So you can either use this in front of all your functions, or
set it once.