#include <iostream>

using namespace std;

class A
{
public:
  A ( int n_, int *b_ );
  A ( const A &ca );
  A ( void );
  ~A ( void );
  operator = ( const A &ca );
  int get_n ( void );
private:
  int n;
  int *b;
};
A::A ( int n_, int *b_ )
{
  n = n_;
  b = new int[ n ];

  for ( int i = 0; i < n; i++ )
  {
    b[ i ] = b_[ i ];
  }
}
A::A ( const A &ca )
{
  n = ca.n;
  b = new int[ n ];

  for ( int i = 0; i < n; i++ )
  {
    b[ i ] = ca.b[ i ];
  }
}
A::operator = ( const A &ca )
{
  n = ca.n;
  b = new int[ n ];

  for ( int i = 0; i < n; i++ )
  {
    b[ i ] = ca.b[ i ];
  }
}
A::A ( void ) : b ( new int[ 0 ] ), n ( 1 )
{
  b[ 0 ] = 0;
}
A::~A ( void )
{
  delete[ ] b;
  b = NULL;
}
int A::get_n ( void )                        //遵循1
{
  return n;
}

int main ( void )
{
  int b[ 2 ] = { 1, 2 };

  A a ( 2, b );

  int &n = a.get_n ( );

  //......

  return ( 0 );
}