[C++] Template

[SkOrPiOn`87]

#include <iostream>

using namespace std;

template<class T>
void bubbleSort( T *array, const int size )
{
   void swap( T * const, T * const );

   for ( int pass = 0; pass < size - 1; pass++ )

      for ( int j = 0; j < size - 1; j++ )

         if ( array[ j ] > array[ j + 1 ] )
            swap( &array[ j ], &array[ j + 1 ] );
}

template <class R>
void swap( R * const element1Ptr, R * const element2Ptr )
{
   R hold = *element1Ptr;
   *element1Ptr = *element2Ptr;
   *element2Ptr = hold;
}

int main()
{
   const int arraySize = 10;
   int a[ arraySize ] = { 2, 6, 4, 8, 10, 12, 89, 68, 45, 37 };
   double b[ arraySize ] = { 2.1, 6.3, 4.2, 8.7, 10.9, 12.6, 89.4, 68.7, 45.1, 37.2 };
   int i;

   cout << "Data items in original order\n";

   for ( i = 0; i < arraySize; i++ )
      cout << a[ i ];

   bubbleSort( a, arraySize );          // sort the array
   cout << "\nData items in ascending order\n";

   for ( i = 0; i < arraySize; i++ )
      cout << a[ i ];
      
   cout << "Data items in original order\n";

   for ( i = 0; i < arraySize; i++ )
      cout << b[ i ];

   bubbleSort( b, arraySize );          // sort the array
   cout << "\nData items in ascending order\n";

   for ( i = 0; i < arraySize; i++ )
      cout << b[ i ];

   cout << endl;
   return 0;
} 

C:\DOCUME~1\federico\IMPOST~1\Temp\ccGuaaaa.o: In function `_tf8_IO_FILE':
//c/docume~1/federico/desktop/untitl~1.cpp(.text$bubbleSort__H1Zi_PX01i_v+0x83): undefined reference to `swap(int *, int *)'
//c/docume~1/federico/desktop/untitl~1.cpp(.text$bubbleSort__H1Zd_PX01i_v+0x88): undefined reference to `swap(double *, double *)'


Come mai mi da questo errore in compilazione?