Source of increment_decrement.cpp

Structures and functions

  1: //increment_decrement.cpp
  2: //Illustrates why you shouldn't use ++ or --, except in a
  3: //standalone statement that increments or decrements a variable.

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

  8: int main()
  9: {
 10:     cout << "\nThis program shows you some examples of situations in "
 11:         "which the increment\nand decrement operators, ++ and --, are "
 12:         "sometimes used, but shouldn't be,\nbecause the code is not "
 13:         "very readable, and is fraught with other dangers.\nStudy the "
 14:         "code, predict the output in each case, and then ...\n\n";

 16:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');
 17:     cout << endl << endl;

 19:     int i, j;

 21:     i = 4;
 22:     j = i++ + 1;
 23:     cout << i << " " << j << endl;
 24:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');

 26:     i = 4;
 27:     j = ++i + 1;
 28:     cout << i << " " << j << endl;
 29:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');

 31:     i = 4;
 32:     j = i-- + 1;
 33:     cout << i << " " << j << endl;
 34:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');

 36:     i = 4;
 37:     j = --i + 1;
 38:     cout << i << " " << j << endl;
 39:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');

 41:     cout << endl;

 43:     i = 25;
 44:     cout << i   << endl;
 45:     cout << ++i << endl;
 46:     cout << i   << endl;
 47:     cout << i++ << endl;
 48:     cout << i   << endl;
 49:     cout << "Press Enter to continue ... ";  cin.ignore(80, '\n');
 50: }