2. Namespace syntax

// mylibrary.h
namespace mylibrary {

    class IntStack {
    public:
        void push( int value );
        //...
    };

    class Rational {
    public:
        Rational& operator=( Rational const& other );
        //...
    };

} // No closing namespace semicolon

Namespaces can be re-opened:

// IntStack.cpp
namespace mylibrary {
    void IntStack::push( int value )
    {
        // ...
    }
}



// Rational.cpp
mylibrary::Rational rat;

namespace mylibrary {
    Rational& Rational::operator=( Rational const& other )
    {
        //...
    }
}