Sams Teach Yourself C++ in 21 Days

More on Program Flow 179

7

Exploring More Complicated whileStatements............................................

The condition tested by a whileloop can be as complex as any legal C++ expression.

This can include expressions produced using the logical &&(AND),||(OR), and!

(NOT) operators. Listing 7.3 is a somewhat more complicated whilestatement.

LISTING7.3 Complex whileLoops

1: // Listing 7.3

2: // Complex while statements

3: #include <iostream>

4:

5: int main()

6: {

7: using namespace std;

8: unsigned short small;

9: unsigned long large;

10: const unsigned short MAXSMALL=65535;

11:

12: cout << “Enter a small number: “;

13: cin >> small;

14: cout << “Enter a large number: “;

15: cin >> large;

16:

17: cout << “small: “ << small << “...”;

18:

19: // for each iteration, test two conditions

20: while (small < large && small < MAXSMALL)

21: {

22: if (small % 5000 == 0) // write a dot every 5k lines

23: cout << “.”;

24:

25: small++;

26: large-=2;

27: }

28:

29: cout << “\nSmall: “ << small << “ Large: “ << large << endl;

30: return 0;

31: }

Enter a small number: 2

Enter a large number: 100000

small: 2.........

Small: 33335 Large: 33334

This program is a game. Enter two numbers, one small and one large. The

smaller number will count up by ones, and the larger number will count down by

twos. The goal of the game is to guess when they’ll meet.

OUTPUT

ANALYSIS