All Categories : C/C++

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- Project 5 -
Taking Charge

In this lesson, you learned more about Visual C++'s operators and about its switch capabilities. You saw the following:

• Combining data types
  
  
• The sizeof operator
  
  
• Using the conditional operator
  
  
• Adding and subtracting one
  
  
• The difficulties involved with nested if-else statements
  
  
• Using switch to improve the readability of nested if-else statements
  
  
• Supplying menus for your users to help them select program options
  
  

Project 5 Listing. Using a switch statement to control a menu.

  1:// Filename: PROJECT5.CPP

  2:// Uses a switch statement to control a user's selection

  3:#include <iostream.h>

  4:

  5:void main()

  6:{

  7:  int menu;

  8:  float charge = 0.00;   // Holds total charge

  9:

 10:  cout << "** Computer Repair Center **" << endl << endl;

 11:  cout << "What work was performed? Here are the choices: " 

 12:       << endl << endl;

 13:  cout << "\t1. Replaced the CPU and RAM" << endl;

 14:  cout << "\t2. Replaced the RAM only" << endl;

 15:  cout << "\t3. Repaired the monitor" << endl;

 16:  cout << "\t4. Fixed stuck keys" << endl;

 17:

 18:  do 

 19:    {

 20:      cout << endl << "What work was performed? ";

 21:      cin >> menu;

 22:    } while ((menu < 1) || (menu > 4));

 23:

 24:  // Store the charge based on the repair person's input

 25:  switch (menu)

 26:  { 

 27:    case 1 :  charge = 200.00F;    // Notice no break here

 28:    case 2 :  charge += 150.00F;

 29:              break;

 30:    case 3 :  charge = 75.00F;

 31:              break; 

 32:    case 4 :  charge = 12.00F;

 33:              break; 

 34:  }

 35:

 36:  // Print the results

 37:  cout.precision(2);

 38:  cout.setf(ios::showpoint);

 39:  cout.setf(ios::fixed);

 40:  cout << endl << "The total charge is $" << charge << endl;

 41:}

Output

** Computer Repair Center **

What work was performed? Here are the choices:

    1. Replaced the CPU and RAM

    2. Replaced the RAM only

    3. Repaired the monitor

    4. Fixed stuck keys

What work was performed? 5

What work was performed? 1

The total charge is $350.00

Description

1: A C++ comment that includes the program's filename.

2: A C++ comment that contains the program's description.

3: cout and cin need information in the IOSTREAM.H header file.

4: Extra blank lines make your program more readable.

5: All functions have names, and the first function in all C++ programs is main().

6: All functions begin with a left brace.

7: Defines an integer variable that will hold the user's chosen menu option.

8: Defines a floating-point variable that will hold a charge.

9: Extra blank lines make your program more readable.

10: Prints a title.

11: Prepares to print the menu.

12: Continues the previous line, printing two new lines.

13: The first menu choice.

14: The second menu choice.

15: The third menu choice.

16: The fourth menu choice.

17: Blank lines help to make your program more readable.

18: The do-while loop always executes at least once, ensuring that the body with the user's question will be shown.

19: while loops use braces to contain the statements that are to be repeated.

20: Asks the user for the desired menu option.

21: Gets the user's input.

22: Keeps looping if the user doesn't enter a valid menu option.

23: Extra blank lines make your program more readable.

24: Place comments throughout your code.

25: Start of the switch statement that will select a case block based on the user's response to the menu.

26: The switch statement encloses its choices in braces.

27: The charge for a CPU repair is stored.

28: The charge for RAM replacement is stored.

29: The break ensures that the execution won't fall through to the subsequent case blocks.

30: The charge for monitor repair is stored.

31: The break ensures that the execution won't fall through to the subsequent case blocks.

32: The charge for the keyboard repair is stored.

33: The break ensures that the execution won't fall through to the subsequent case blocks.

34: A final closing switch brace is always required.

35: Extra blank lines make your program more readable.

36: Place comments throughout your code.

37: Ensures that two decimal places print.

38: Makes sure the decimal point always appears.

39: Guards against scientific notation.

40: Prints the total charge.

41: A final brace ends all main() functions.

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22: Always check the user's input for validation.

27: Notice that there is no break here. If there is a CPU repair, there will always be a RAM replacement (see the menu), so execution will fall through to the second case as well.

28: Removing a break lets you cascade case code blocks.

29: If execution fell through from the previous case, charge will hold $350. Otherwise, if the user selected only RAM replacement, the charge will be only $150.00.

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