Home > Articles

Methods: A Deeper Look

This chapter is from the book

This chapter is from the book

7.10 Scope of Declarations

You’ve seen declarations of C# entities, such as classes, methods, properties, variables and parameters. Declarations introduce names that can be used to refer to such C# entities. The scope of a declaration is the portion of the app that can refer to the declared entity by its unqualified name. Such an entity is said to be “in scope” for that portion of the app. This section introduces several important scope issues. The basic scope rules are as follows:

  1. The scope of a parameter declaration is the body of the method in which the declaration appears.

  2. The scope of a local-variable declaration is from the point at which the declaration appears to the end of the block containing the declaration.

  3. The scope of a local-variable declaration that appears in the initialization section of a for statement’s header is the body of the for statement and the other expressions in the header.

  4. The scope of a method, property or field of a class is the entire body of the class. This enables non-static methods and properties of a class to use any of the class’s fields, methods and properties, regardless of the order in which they’re declared. Similarly, static methods and properties can use any of the static members of the class.

Any block may contain variable declarations. If a local variable or parameter in a method has the same name as a field, the field is hidden until the block terminates—in Chapter 10, we discuss how to access hidden fields. A compilation error occurs if a nested block in a method contains a variable with the same name as a local variable in an outer block of the method. The app in Fig. 7.8 demonstrates scoping issues with fields and local variables.

 1   // Fig. 7.8: Scope.cs
 2   // Scope class demonstrates static- and local-variable scopes.
 3   using System;
 4
 5   class Scope
 6   {
 7      // static variable that's accessible to all methods of this class
 8      private static int x = 1;                                        
 9
10      // Main creates and initializes local variable x
11      // and calls methods UseLocalVariable and UseStaticVariable
12      static void Main()
13      {
14         int x = 5; // method's local variable x hides static variable x
15
16         Console.WriteLine($"local x in method Main is {x}");
17
18         // UseLocalVariable has its own local x
19         UseLocalVariable();
20
21         // UseStaticVariable uses class Scope's static variable x
22         UseStaticVariable();
23
24         // UseLocalVariable reinitializes its own local x
25         UseLocalVariable();
26
27         // class Scope's static variable x retains its value
28         UseStaticVariable();
29
30         Console.WriteLine($"\nlocal x in method Main is {x}");
31      }
32
33      // create and initialize local variable x during each call
34      static void UseLocalVariable()
35      {
36         int x = 25; // initialized each time UseLocalVariable is called
37
38         Console.WriteLine(
39            $"\nlocal x on entering method UseLocalVariable is {x}");
40         ++x; // modifies this method's local variable x
41         Console.WriteLine(
42            $"local x before exiting method UseLocalVariable is {x}");
43      }
44
45      // modify class Scope's static variable x during each call
46      static void UseStaticVariable()
47      {
48         Console.WriteLine("\nstatic variable x on entering method " +
49            $"UseStaticVariable is {x}");
50         x *= 10; // modifies class Scope's static variable x
51         Console.WriteLine("static variable x before exiting " +
52            $"method UseStaticVariable is {x}");
53      }
54   }
local x in method Main is 5

local x on entering method UseLocalVariable is 25
local x before exiting method UseLocalVariable is 26

static variable x on entering method UseStaticVariable is 1
static variable x before exiting method UseStaticVariable is 10

local x on entering method UseLocalVariable is 25
local x before exiting method UseLocalVariable is 26

static variable x on entering method UseStaticVariable is 10
static variable x before exiting method UseStaticVariable is 100

local x in method Main is 5

Fig. 7.8 | Scope class demonstrates static and local-variable scopes.

Line 8 declares and initializes the static variable x to 1. This static variable is hidden in any block (or method) that declares a local variable named x. Method Main (lines 12–31) declares local variable x (line 14) and initializes it to 5. This local variable’s value is output to show that static variable x (whose value is 1) is hidden in method Main. The app declares two other methods—UseLocalVariable (lines 34–43) and UseStaticVariable (lines 46–53)—that each take no arguments and do not return results. Method Main calls each method twice (lines 19–28). Method UseLocalVariable declares local variable x (line 36). When UseLocalVariable is first called (line 19), it creates local variable x and initializes it to 25 (line 36), outputs the value of x (lines 38–39), increments x (line 40) and outputs the value of x again (lines 41–42). When UseLocalVariable is called a second time (line 25), it re-creates local variable x and reinitializes it to 25, so the output of each call to UseLocalVariable is identical.

Method UseStaticVariable does not declare any local variables. Therefore, when it refers to x, static variable x (line 8) of the class is used. When method UseStaticVariable is first called (line 22), it outputs the value (1) of static variable x (lines 48–49), multiplies the static variable x by 10 (line 50) and outputs the value (10) of static variable x again (lines 51–52) before returning. The next time method UseStaticVariable is called (line 28), the static variable has its modified value, 10, so the method outputs 10, then 100. Finally, in method Main, the app outputs the value of local variable x again (line 30) to show that none of the method calls modified Main’s local variable x, because the methods all referred to variables named x in other scopes.

  • + 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