Point and Swap

[Kayoss]

This code successfully swaps the variables, but I'm wondering why the address for the first element (2) is greater than the address for the second element (3)?

#include <iostream>

using namespace std;

void swap( int * const, int * const ); //  prototype

int main()
{

   int array[2] = {2,3}; 

   int *arrayPTR = array; 
   int *arrayPTR1 = &array[1]; 


   cout << *arrayPTR << "  " << &arrayPTR << endl; // first element and address
   cout << *arrayPTR1 << "  " << &arrayPTR1 << endl; // second element and address
   cout << "SWAP" << endl;


   // the following code swaps elements in array, defined after   function main

   swap( &array[0], &array[0 + 1] );


   cout << *arrayPTR << "  " << &arrayPTR << endl;
   cout << *arrayPTR1 << "  " << &arrayPTR1 << endl;


return 0;

}

// defines swap function, swaps values in array

void swap( int * const element1PTR, int * const element2PTR )
{
	int hold = *element1PTR;
	*element1PTR = *element2PTR;
	*element2PTR = hold;

} // end function swap

[hk_mp5kpdw]

Who says data placed in memory has to start from the bottom and move up? It's entirely possible that it could be placed in the higher addresses first and move down from there.

[7stud]

On my system, when I run this program:

#include<iostream>
using namespace std;

int main()
{
	int arr[2]={2,3};
	
	cout<<arr<<endl
		<<&arr[1]<<endl;

	return 0;
}

I get this output:

006BFDF0
006BFDF4

[Kayoss]

Hmm I suppose it doesn't have to...it just has for me up until this point.

I get:

0012FF74
0012FF70

[7stud]

Who says data placed in memory has to start from the bottom and move up?

Whaaa?? All the pictures in my book have the memory going from left to right?

[Dave_Sinkula]

Kayoss: Array members must be in an increasing order, but your program is not showing that -- it is showing the address of some pointers that hold the address you want.

#include <iostream>
using namespace std;

int main()
{
   int array[2] = {2,3};
   cout << &array[0] << ' ' << array[0] << '\n';
   cout << &array[1] << ' ' << array[1] << '\n';
   return 0;
}

/* my output
0012FF84 2
0012FF88 3
*/

[edit]

#include <iostream>
using namespace std;

void swap( int * const element1PTR, int * const element2PTR )
{
	int hold = *element1PTR;
	*element1PTR = *element2PTR;
	*element2PTR = hold;
}

int main()
{
   int array[2]   = {2,3};
   int *arrayPTR  = array;
   int *arrayPTR1 = &array[1];

   cout << *arrayPTR  << "  " << arrayPTR << endl; // first element and address
   cout << *arrayPTR1 << "  " << arrayPTR1 << endl; // second element and address
   cout << "SWAP" << endl;

   // the following code swaps elements in array, defined after   function main
   swap( &array[0], &array[0 + 1] );
   cout << *arrayPTR  << "  " << arrayPTR << endl;
   cout << *arrayPTR1 << "  " << arrayPTR1 << endl;

   return 0;
}

/* my output
2  0012FF84
3  0012FF88
SWAP
3  0012FF84
2  0012FF88
*/

[Kayoss]

Thank you Dave!