Home > Articles

Methods: A Deeper Look

  • Print
  • + Share This
This chapter is from the book

This chapter is from the book

7.9 Case Study: A Game of Chance; Introducing Enumerations

One popular game of chance is the dice game known as “craps,” which is played in casinos and back alleys throughout the world. The rules of the game are straightforward:

  • You roll two dice. Each die has six faces, which contain one, two, three, four, five and six spots, respectively. After the dice have come to rest, the sum of the spots on the two upward faces is calculated. If the sum is 7 or 11 on the first throw, you win. If the sum is 2, 3 or 12 on the first throw (called “craps”), you lose (i.e., “the house” wins). If the sum is 4, 5, 6, 8, 9 or 10 on the first throw, that sum becomes your “point.” To win, you must continue rolling the dice until you “make your point” (i.e., roll that same point value). You lose by rolling a 7 before making your point.

The app in Fig. 7.7 simulates the game of craps, using methods to define the logic of the game. The Main method (lines 24–80) calls the static RollDice method (lines 83–94) as needed to roll the two dice and compute their sum. The four sample outputs show winning on the first roll, losing on the first roll, losing on a subsequent roll and winning on a subsequent roll, respectively. Variable randomNumbers (line 8) is declared static, so it can be created once during the program’s execution and used in method RollDice.

 1   // Fig. 7.7: Craps.cs
 2   // Craps class simulates the dice game craps.
 3   using System;
 4
 5   class Craps
 6   {
 7      // create random-number generator for use in method RollDice
 8      private static Random randomNumbers = new Random();
 9
10      // enumeration with constants that represent the game status
11      private enum Status {Continue, Won, Lost}             
12
13      // enumeration with constants that represent common rolls of the dice
14      private enum DiceNames
15      {                     
16         SnakeEyes = 2,     
17         Trey = 3,          
18         Seven = 7,         
19         YoLeven = 11,      
20         BoxCars = 12       
21      }                     
22
23      // plays one game of craps
24      static void Main()
25      {
26         // gameStatus can contain Continue, Won or Lost
27         Status gameStatus = Status.Continue;
28         int myPoint = 0; // point if no win or loss on first roll
29
30         int sumOfDice = RollDice(); // first roll of the dice
31
32         // determine game status and point based on first roll
33         switch ((DiceNames) sumOfDice)
34         {
35            case DiceNames.Seven: // win with 7 on first roll    
36            case DiceNames.YoLeven: // win with 11 on first roll 
37               gameStatus = Status.Won;                          
38               break;
39            case DiceNames.SnakeEyes: // lose with 2 on first roll
40            case DiceNames.Trey: // lose with 3 on first roll     
41            case DiceNames.BoxCars: // lose with 12 on first roll 
42               gameStatus = Status.Lost;                          
43               break;
44            default: // did not win or lose, so remember point  
45               gameStatus = Status.Continue; // game is not over
46               myPoint = sumOfDice; // remember the point       
47               Console.WriteLine($"Point is {myPoint}");        
48               break;
49         }
50
51         // while game is not complete
52         while (gameStatus == Status.Continue) // game not Won or Lost
53         {
54            sumOfDice = RollDice(); // roll dice again
55
56            // determine game status
57            if (sumOfDice == myPoint) // win by making point
58            {
59               gameStatus = Status.Won;
60            }
61            else
62            {
63               // lose by rolling 7 before point
64               if (sumOfDice == (int) DiceNames.Seven)
65               {
66                  gameStatus = Status.Lost;
67               }
68            }
69         }
70
71         // display won or lost message
72         if (gameStatus == Status.Won)
73         {
74            Console.WriteLine("Player wins");
75         }
76         else
77         {
78            Console.WriteLine("Player loses");
79         }
80      }
81
82      // roll dice, calculate sum and display results
83      static int RollDice()
84      {
85         // pick random die values
86         int die1 = randomNumbers.Next(1, 7); // first die roll
87         int die2 = randomNumbers.Next(1, 7); // second die roll
88
89         int sum = die1 + die2; // sum of die values
90
91         // display results of this roll
92         Console.WriteLine($"Player rolled {die1} + {die2} = {sum}");
93         return sum; // return sum of dice
94      }
95   }
Player rolled 2 + 5 = 7
Player wins
Player rolled 2 + 1 = 3
Player loses
Player rolled 2 + 4 = 6
Point is 6
Player rolled 3 + 1 = 4
Player rolled 5 + 5 = 10
Player rolled 6 + 1 = 7
Player loses
Player rolled 4 + 6 = 10
Point is 10
Player rolled 1 + 3 = 4
Player rolled 1 + 3 = 4
Player rolled 2 + 3 = 5
Player rolled 4 + 4 = 8
Player rolled 6 + 6 = 12
Player rolled 4 + 4 = 8
Player rolled 4 + 5 = 9
Player rolled 2 + 6 = 8
Player rolled 6 + 6 = 12
Player rolled 6 + 4 = 10
Player wins

Fig. 7.7 | Craps class simulates the dice game craps.

7.9.1 Method RollDice

In the rules of the game, the player must roll two dice on the first roll and must do the same on all subsequent rolls. We declare method RollDice (lines 83–94) to roll the dice and compute and display their sum. Method RollDice is declared once, but it’s called from two places (lines 30 and 54) in method Main, which contains the logic for one complete game of craps. Method RollDice takes no arguments, so it has an empty parameter list. Each time it’s called, RollDice returns the sum of the dice as an int. Although lines 86 and 87 look the same (except for the die names), they do not necessarily produce the same result. Each of these statements produces a random value in the range 1–6. Variable randomNumbers (used in lines 86–87) is not declared in the method. Rather it’s declared as a private static variable of the class and initialized in line 8. This enables us to create one Random object that’s reused in each call to RollDice.

7.9.2 Method Main’s Local Variables

The game is reasonably involved. The player may win or lose on the first roll or may win or lose on any subsequent roll. Method Main (lines 24–80) uses local variable gameStatus (line 27) to keep track of the overall game status, local variable myPoint (line 28) to store the “point” if the player does not win or lose on the first roll and local variable sumOfDice (line 30) to maintain the sum of the dice for the most recent roll. Variable myPoint is initialized to 0 to ensure that the app will compile. If you do not initialize myPoint, the compiler issues an error, because myPoint is not assigned a value in every case of the switch statement—thus, the app could try to use myPoint before it’s definitely assigned a value. By contrast, gameStatus does not require initialization because it’s assigned a value in every branch of the switch statement—thus, it’s guaranteed to be initialized before it’s used. However, as good practice, we initialize it anyway.

7.9.3 enum Type Status

Local variable gameStatus (line 27) is declared to be of a new type called Status, which we declared in line 11. Status is a user-defined type called an enumeration, which declares a set of constants represented by identifiers. An enumeration is introduced by the keyword enum and a type name (in this case, Status). As with a class, braces ({ and }) delimit the body of an enum declaration. Inside the braces is a comma-separated list of enumeration constants—by default, the first constant has the value 0 and each subsequent constant’s value is incremented by 1. The enum constant names must be unique, but the value associated with each constant need not be. Type Status is declared as a private member of class Craps, because Status is used only in that class.

Variables of type Status should be assigned only one of the three constants declared in the enumeration. When the game is won, the app sets local variable gameStatus to Status.Won (lines 37 and 59). When the game is lost, the app sets gameStatus to Status.Lost (lines 42 and 66). Otherwise, the app sets gameStatus to Status.Continue (line 45) to indicate that the dice must be rolled again.

7.9.4 The First Roll

Line 30 in method Main calls RollDice, which picks two random values from 1 to 6, displays the value of the first die, the value of the second die and the sum of the dice, and returns the sum of the dice. Method Main next enters the switch statement at lines 33–49, which uses the sumOfDice value to determine whether the game has been won or lost, or whether it should continue with another roll.

7.9.5 enum Type DiceNames

The sums of the dice that would result in a win or loss on the first roll are declared in the DiceNames enumeration in lines 14–21. These are used in the switch statement’s cases. The identifier names use casino parlance for these sums. In the DiceNames enumeration, we assign a value explicitly to each identifier name. When the enum is declared, each constant in the enum declaration is a constant value of type int. If you do not assign a value to an identifier in the enum declaration, the compiler will do so. If the first enum constant is unassigned, the compiler gives it the value 0. If any other enum constant is unassigned, the compiler gives it a value one higher than that of the preceding enum constant. For example, in the Status enumeration, the compiler implicitly assigns 0 to Status.Continue, 1 to Status.Won and 2 to Status.Lost.

7.9.6 Underlying Type of an enum

You could also declare an enum’s underlying type to be byte, sbyte, short, ushort, int, uint, long or ulong by writing

private enum MyEnum : typeName {Constant1, Constant2, ...}

where typeName represents one of the integral simple types.

7.9.7 Comparing Integers and enum Constants

If you need to compare a simple integral type value to the underlying value of an enumeration constant, you must use a cast operator to make the two types match—there are no implicit conversions between enum and integral types. In the switch expression (line 33), we use the cast operator to convert the int value in sumOfDice to type DiceNames and compare it to each of the constants in DiceNames. Lines 35–36 determine whether the player won on the first roll with Seven (7) or YoLeven (11). Lines 39–41 determine whether the player lost on the first roll with SnakeEyes (2), Trey (3) or BoxCars (12). After the first roll, if the game is not over, the default case (lines 44–48) saves sumOfDice in myPoint (line 46) and displays the point (line 47).

Additional Rolls of the Dice

If we’re still trying to “make our point” (i.e., the game is continuing from a prior roll), the loop in lines 52–69 executes. Line 54 rolls the dice again. If sumOfDice matches myPoint in line 57, line 59 sets gameStatus to Status.Won, and the loop terminates because the game is complete. In line 64, we use the cast operator (int) to obtain the underlying value of DiceNames.Seven so that we can compare it to sumOfDice. If sumOfDice is equal to Seven (7), line 66 sets gameStatus to Status.Lost, and the loop terminates because the game is over. When the game completes, lines 72–79 display a message indicating whether the player won or lost, and the app terminates.

Control Statements in the Craps Example

Note the use of the various program-control mechanisms we’ve discussed. The Craps class uses two methods—Main and RollDice (called twice from Main)—and the switch, while, if...else and nested if control statements. Also, notice that we use multiple case labels in the switch statement to execute the same statements for sums of Seven and YoLeven (lines 35–36) and for sums of SnakeEyes, Trey and BoxCars (lines 39–41).

Code Snippets for Auto-Implemented Properties

Visual Studio has a feature called code snippets that allows you to insert predefined code templates into your source code. One such snippet enables you to easily create a switch statement with cases for all possible values for an enum type. Type switch in the C# code then press Tab twice. If you specify a variable of an enum type in the switch statement’s expression and press Enter, a case for each enum constant will be generated automatically.

To get a list of all available code snippets, type Ctrl + k, Ctrl + x. This displays the Insert Snippet window in the code editor. You can navigate through the Visual C# snippet folders with the mouse to see the snippets. This feature also can be accessed by right clicking in the source code editor and selecting the Insert Snippet... menu item.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020