//	Ex742.cc

//	Sec. 7.4 of lecture
//	Pointer as OUTPUT parameter

#include <iostream.h>

//	n and xp are OUTPUT parameters
//void Allocate(int n, double* xp);	// VERY WRONG
//void Allocate(int & n, double* xp);	// WRONG
void Allocate(int & n, double* & xp);	// RIGHT

main()
{
 int    length=0;
 double *pp = 0;	// initialize pointer with NULL
 
 Allocate(length, pp);
 
 cout << "I allocated " << length << " double numbers";
 cout << " at address  " << pp << endl;
 
 delete [] pp;
}


//void Allocate(int n, double* xp);	// VERY WRONG
//void Allocate(int & n, double* xp)	// WRONG
void Allocate(int & n, double* & xp)	// RIGHT
{
 cout << " Length of array : ";
 cin  >> n;
 
 xp = new double [n];
 
 return;
}