Modify this program to use namespaces and separate compilation. using c++ -Put the class definition and other function declarations Programming Projects 517 in one file. -Place the implementations in a separate file. -Distribute the namespace definition across the two files. -Place the demonstration program in a third file. -To provide access to names in namespaces, you may use local using declarations such as using std::cout; or use local using directives such as using namespace std; inside a block, or qualify names using the names of namespaces, such as std::cout. -You may not use global namespace directives such as the following which are not in a block and apply to the entire file: using namespace std;"     code #include #include using namespace std; class PFArrayD { public: PFArrayD( ); //Initializes with a capacity of 50. PFArrayD(int capacityValue); PFArrayD(const PFArrayD& pfaObject); void addElement(double element); //Precondition: The array is not full. //Postcondition: The element has been added. bool full( ) const { return (capacity == used); } //Returns true if the array is full, false otherwise. int getCapacity( ) const { return capacity; } int getNumberUsed( ) const { return used; } void emptyArray( ){ used = 0; } //Empties the array. double& operator[](int index); //Read and change access to elements 0 through numberUsed - 1. PFArrayD& operator =(const PFArrayD& rightSide); ~PFArrayD( ); private: double *a; //For an array of doubles int capacity; //For the size of the array int used; //For the number of array positions currently in use }; PFArrayD::PFArrayD( ) :capacity(50), used(0) { a = new double[capacity]; } PFArrayD::PFArrayD(int size) :capacity(size), used(0) { a = new double[capacity]; } PFArrayD::PFArrayD(const PFArrayD& pfaObject) :capacity(pfaObject.getCapacity( )), used(pfaObject.getNumberUsed( )) { a = new double[capacity]; for (int i = 0; i < used; i++) a[i] = pfaObject.a[i]; } void PFArrayD::addElement(double element) { if (used >= capacity) { cout << "Attempt to exceed capacity in PFArrayD.\n"; exit(0); } a[used] = element; used++; } double& PFArrayD::operator[](int index) { if (index >= used) { cout << "Illegal index in PFArrayD.\n"; exit(0); } } PFArrayD& PFArrayD::operator =(const PFArrayD& rightSide) { if (capacity != rightSide.capacity) { delete [] a; a = new double[rightSide.capacity]; } capacity = rightSide.capacity; used = rightSide.used; for (int i = 0; i < used; i++) a[i] = rightSide.a[i]; return *this; } PFArrayD::~PFArrayD( ) { delete[] a; } //PROGRAM TO TEST PFArrayD #include using namespace std; class PFArrayD { }; void testPFArrayD( ); //Conducts one test of the class PFArrayD. int main( ) { cout << "This program tests the class PFArrayD.\n"; char ans; do { testPFArrayD( ); cout << "Test again? (y/n) "; cin >> ans; } while ((ans == 'y') || (ans == 'Y')); return 0; } void testPFArrayD( ) { int cap; cout << "Enter capacity of this super array: "; cin >> cap; PFArrayD temp(cap); cout << "Enter up to " << cap << " nonnegative numbers.\n"; cout << "Place a negative number at the end.\n"; double next; cin >> next; while ((next >= 0) && (!temp.full( ))) { temp.addElement(next); cin >> next; } cout << "You entered the following " << temp.getNumberUsed( ) << " numbers:\n"; int index; int count = temp.getNumberUsed( ); for (index = 0; index < count; index++) cout << temp[index] << " "; cout << endl; cout << "(plus a sentinel value.)\n"; }