Source of ptr_swap.cpp

Structures and functions

  1: // Filename: PTR_SWAP.CPP
  2: // Purpose:  Illustrates the passing of pointer parameters.

  4: #include <iostream>
  5: using namespace std;

  7: #include "PAUSE.H"


 10: void Swap(/* inout */ int& a, /* inout */ int& b)
 11: // Pre:  "a" and "b" have been initialized.
 12: // Post: The values of "a" and "b" have been swapped.
 13: {
 14:     int temp = a;
 15:     a = b;
 16:     b = temp;
 17: }


 20: void Swap(/* inout */ int* ap, /* inout */ int* bp)
 21: // Pre:  "ap" and "bp" contain the addresses of integer values.
 22: // Post: The integer values in the locations pointed to by ap
 23: //       have been swapped.
 24: {
 25:     int temp = *ap;
 26:     *ap = *bp;
 27:     *bp = temp;
 28: }


 31: int main()
 32: {
 33:     cout << "\nThis program show the connection between pointer parameters"
 34:          << "\nand reference parameters."
 35:          << "\nStudy the source code and the output simultaneously.\n\n";

 37:     int m = 7;
 38:     int n = -3;

 40:     cout << endl;
 41:     cout << "Original values of m and n:  " << m << " " << n << endl;
 42:     Pause(29);

 44:     // This call uses the Swap with reference parameters:
 45:     Swap(m, n);
 46:     cout << "Swapped values of m and n:   " << m << " " << n << endl;
 47:     Pause(29);

 49:     // This call uses the Swap with pointer parameters:
 50:     Swap(&m, &n);
 51:     cout << "And then swapped back again: " << m << " " << n << endl;
 52:     Pause(29);

 54:     return 0;
 55: }