//  Your name goes here
#include <conio.h> #include <fstream.h>
#include <iomanip.h> #include <iostream.h>
#include <string.h> #include <stdlib.h>
  /* What are pointers for:
		* Accessing array elements
		* Passing arguments to a function when the function needs to modify the
		  original argument.
		* Passing arrays and strings to functions
	  Every byte in the computers memory has an address.  Your program, when loaded into
	  memory, occupies a certain range of these addresses.  That means that every
	  variable and every function in your program starts at a particular address.

	The Address-of Operator &     */
  int var4 = 44 ;
  int var5 = 55 ;
  int var6 = 66 ;

void main ( )
 {
  cout << endl << "var4 = " << var4 << "  var5 = " << var5 << "  var6 = "<<var6<<endl;
  cout << endl << "var4 = " << &var4
		 << endl << "var5 = " << &var5
		 << endl << "var6 = " << &var6 << endl;
  cout << endl << "Notice the addresses are ascending for global." << endl ;

  int var1 = 11 ;
  int var2 = 22 ;
  int var3 = 33 ;
  cout << endl << "var1 = " << var1 << "  var2 = " << var2 << "  var3 = "<<var3<<endl;
  cout << endl << "var1 = " << &var1
		 << endl << "var2 = " << &var2
		 << endl << "var3 = " << &var3;
  cout << endl << "Notice the addresses are descending for local." << endl ;
						 /* The << insertion operator interprets the addresses in hex,
							 as indicated by the prefix 0x.
							 With local variables, addresses appear in descending order
							 because local variables are stored on the stack.
							 A stack works like a spring-loaded devices that hold trays in
							 cafeterias.  When you put a tray on top, the stack sinks down a
							 little; when you take a tray off, it pops up.  The last tray
							 placed on the stack is always the first tray removed.  
							 With global variaables, they would have ascending addresses, since
							 global variables are stored on a heap, which grows upward.
 Pointer Variables:  A variable that holds an address value is called a pointer
                     variable, or simply a pointer. 
  */
  int *ptr    ;         // pointer to an integer
                        // The * means pointer to.  Defines ptr as a pointer to int. 
  ptr = &var1 ;         // pointer points to var1
  cout << endl << "ptr = " << ptr << endl   ;

  char  *cprt  ;        // pointer to char
  int   *iprt  ;        // pointer to integer
  float *fprt  ;        // pointer to float

//** Make sure you give every pointer variable a valid address value before using it.
/*
// Accessing the Variable Pointed To:
  ptr = &var1 ;         // pointer points to var1
  cout << endl << "ptr = " << ptr << endl   ;
  cout << endl << "*ptr = " << *ptr << endl ;

  ptr = &var2 ;         // pointer points to var2
  cout << endl << "ptr = " << ptr << endl   ;
  cout << endl << "*ptr = " << *ptr << endl ;

// Using a pointer to assign a value to a variable, and then to assign that value to
//   another variable.
  ptr = &var1  ;
  *ptr = 37    ;
  var2 = *ptr  ;
  cout << endl << endl << "var2 = " << var2 << endl ;   // varify var2 = 37
*/
 }                      //   end of main
//******************************************************************************