Go back to Richel Bilderbeek's homepage.
Go back to Richel Bilderbeek's C++ page.
Keyword to make groups of functions
and classes.
To
call something from a certain namespace, write
the namespace's name in front, followed by the scope operator, ::.
Functions and classes
that are not put into a namespace reside in the global namespace.
The
default namespace used is the global namespace. You
can change this by using the keyword using.
All
STL functions and classes are in the namespace
std.
In
the example, three versions of the function SayHello reside in different namespaces: loud, soft and the global namespace.
namespace
loud
{
void SayHello() { std::cout
<< "HELLO WORLD!\n"; }
}
//SayHello in the global namespace, ::SayHello()
void SayHello() { std::cout << "Hello world\n"; }
namespace
soft
{
void SayHello() { std::cout
<< "H.e.l.l.o w.o.r.l.d...\n"; }
}
{
loud::SayHello(); //Call
loud::SayHello
::SayHello(); //Explicity
call SayHello from global namespace
SayHello(); //Call the
SayHello used, which is ::SayHello by default
using soft::SayHello; //Start using
soft::SayHello
SayHello(); //Call the
SayHello used, which is soft::SayHello now
soft::SayHello(); //Call
soft::SayHello
}
This results in the following screen output:
HELLO WORLD!
Hello world
Hello world
H.e.l.l.o w.o.r.l.d...
H.e.l.l.o w.o.r.l.d...
Go back to Richel Bilderbeek's C++ page.
Go back to Richel Bilderbeek's homepage.