ns3.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

// Build don't link: 
namespace foo{
 void eine_funktion(int)
 {}
}

using namespace foo;

namespace foo{
 void eine_funktion(int,int)
 {}
}

void andere_funktion()
{
  eine_funktion(3,4);
}