Evaluation Copy. C# Essentials. Student Guide Revision 4.5. Object Innovations Course 4102

Transcription

1 C# Essentials Student Guide Revision 4.5 Object Innovations Course 4102

2 C# Essentials Rev. 4.5 Student Guide Information in this document is subject to change without notice. Companies, names and data used in examples herein are fictitious unless otherwise noted. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of Object Innovations. Product and company names mentioned herein are the trademarks or registered trademarks of their respective owners. Author: Robert J. Oberg Special Thanks: Johnathon McAlister Copyright 2012 Object Innovations Enterprises, LLC All rights reserved. Object Innovations Printed in the United States of America. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC ii

3 Table of Contents (Overview) Chapter 1.NET: What You Need to Know Chapter 2 C# Overview for the Sophisticated Programmer Chapter 3 Object-Oriented Programming in C# Chapter 4 Chapter 5 Chapter 6 C# and the.net Framework Delegates and Events Introduction to Windows Forms Chapter 7 New Features in C# 4.0 and C# 5.0 Appendix A Using Visual Studio 2012 Appendix B Language Integrated Query (LINQ) Appendix C Visual Studio 2010 and Visual Studio 2012 Appendix D Learning Resources Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC iii

4 Directory Structure The course software installs to the root directory C:\OIC\CsEss. Example programs for each chapter are in named subdirectories of chapter directories Chap01, Chap02, and so on. Example programs for Appendices A, B and C are in the directories AppA, AppB and AppC. The Labs directory contains one subdirectory for each lab, named after the lab number. Starter code is frequently supplied, and answers are provided in the chapter directories. The CaseStudy directory contains a case study in multiple steps. The Demos directory is provided for performing in-class demonstrations led by the instructor. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC iv

5 Table of Contents (Detailed) Chapter 1.NET: What You Need to Know... 1 Getting Started... 3.NET: What Is Really Happening... 4.NET Programming in a Nutshell... 5.NET Program Example... 6 Viewing the Assembly... 7 Viewing Intermediate Language... 8 Understanding.NET... 9 Visual Studio Creating a Console Application Adding a C# File Using the Visual Studio Text Editor IntelliSense Build and Run the Project Pausing the Output Visual C# and GUI Programs NET Documentation Summary Chapter 2 C# Overview for the Sophisticated Programmer Hello, World Compiling, Running (Command Line) Program Structure Namespaces Variables Input in C# More about Classes InputWrapper Class Sample Program Input Wrapper Implementation Compiling Multiple Files Control Structures switch C# Operators Precedence Table Types in C# Simple Types Types in System Namespace Integer Data Types Floating Point Data Types Implicit Conversions Explicit Conversions Boolean Data Type Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC v

6 struct Uninitialized Variables Enumeration Types Nullable Types Reference Types Class Types object string Copying Strings StringBuilder Class Classes and Structs Static and Instance Methods Method Parameters No Freestanding Functions in C# Classes with All Static Methods Parameter Passing Parameter Terminology Value Parameters Reference Parameters Reference Parameters Example Output Parameters Output Parameters Example Structure Parameters Class Parameters Method Overloading Variable Length Parameter Lists Arrays One-Dimensional Arrays System.Array Jagged Arrays Rectangular Arrays foreach for Arrays Boxing and Unboxing Implicitly Typed Variables Implicitly Typed Variables Example Output in C# Formatting Formatting Example Exceptions Exception Example Checked Integer Arithmetic Throwing New Exceptions finally System.Exception Lab Summary Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC vi

7 Chapter 3 Object-Oriented Programming in C# C# Object-Oriented Features Encapsulation and Accessors Asymmetric Accessor Accessibility Using a Property Indexers Visual Studio Console Projects Files in Skeleton Solution Source Files Bank Example Account Class Constructors Static Members Static in Main Static Constructor Constant and Readonly Fields Auto-Implemented Properties Auto-Implemented Property Example Inheritance in C# New Version of Base Class Features of the New Base Class Derived Class Overriding a Virtual Function Abstract Classes Keyword: abstract Derived Class Test Program Sealed Classes Access Control and Assemblies Internal Accessibility Assembly Example Class Libraries Lab Summary Chapter 4 C# and the.net Framework Components and OO in C# Interfaces in C# Interface Inheritance Programming with Interfaces Implementing Interfaces Using an Interface Example: SmallInterface Dynamic Use of Interfaces Example: TryInterfaces is Operator as Operator Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC vii

8 Resolving Ambiguity Explicit Interface Implementation Explicit Interfaces Test Program System.Object Collections ArrayList ArrayList Methods Example: StringList IEnumerable and IEnumerator Using Enumerators Collections of User-Defined Objects Account Class AccountList Class Copy Semantics in C# Deep Copy and ICloneable Lab 4A Writing Generic Code Using a Class of object Generic Types Generic Syntax in C# Generic Example Generic Client Code System.Collections.Generic Lab 4B Object Initializers Collection Initializers Anonymous Types Attributes Attribute Usage Example Summary Chapter 5 Delegates and Events Overview of Delegates and Events Callbacks and Delegates Usage of Delegates Declaring a Delegate Defining a Method Creating a Delegate Object Calling a Delegate Random Number Generation A Random Array Anonymous Methods Combining Delegate Objects Account.cs DelegateAccount.cs Lambda Expressions Named Method Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC viii

9 Anonymous Method Lambda Expression Example Events Events in C# and.net Client Side Event Code Chat Room Example Lab Summary Chapter 6 Introduction to Windows Forms Creating a Windows Forms App Partial Classes Windows Forms Event Handling Add Events for a Control Events Documentation Closing a Form ListBox Control ListBox Example Lab Summary Chapter 7 New Features in C# 4.0 and C# dynamic Type Runtime Error Example dynamic versus object Behavior of object Behavior of dynamic Named Arguments Optional Arguments Book Class Using Optional Arguments Variance in Generic Interfaces Covariance Example Variance with IComparer<T> Interfaces with Variance Support Contravariance Example Asynchronous Programs in C# Task and Task<TResult> Aysnc Methods Async Example Synchronous Call Async Call Threading Summary Appendix A Using Visual Studio A Visual Studio Solution Toolbars Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC ix

10 Customizing a Toolbar Creating a Console Application Adding a C# File Using the Visual Studio Text Editor Build and Run the Bytes Project Running the Bytes Project Executable File Location Managing Configurations Project Configurations Creating a New Configuration Setting Configuration Build Settings Debugging Breakpoints Watch Variables Debug Toolbar Stepping with the Debugger Demo: Stepping with the Debugger Call Stack and Call Hierarchy Multiple-Project Solution Demo Adding a Reference Project Dependencies Startup Project Hidden Files Summary Appendix B Language Integrated Query (LINQ) Language-Integrated Query (LINQ) LINQ Example Using IEnumerable<T> Basic LINQ Query Operators Obtaining a Data Source LINQ Query Example Filtering Ordering Aggregation Obtaining Lists and Arrays Deferred Execution Summary Appendix C Visual Studio 2010 and Visual Studio VS 2010 Solutions with VS NET Framework Versions NET Version Issues Summary Appendix D Learning Resources Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC x

11 CsEss Chapter 1 Chapter 1.NET: What You Need to Know Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 1

12 CsEss Chapter 1.NET: What You Need to Know Objectives After completing this unit you will be able to: Describe the essentials of creating and running a program in the.net environment. Build and run a simple C# program. Use the ILDASM tool to view intermediate language. Use Visual Studio 2012 as an effective environment for creating C# programs. Use the.net Framework SDK documentation. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 2

13 CsEss Chapter 1 Getting Started From a programmer s perspective, a beautiful thing about.net is that you scarcely need to know anything about it to start writing programs for the.net environment. You write a program in a high-level language (such as C#), a compiler creates an executable.exe file (called an assembly), and you run that.exe file. Even very simple programs, if they are designed to do something interesting, such as perform output, will require that the program employ the services of library code. A large library, called the.net Framework Class Library, comes with.net, and you can use all of the services of this library in your programs. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 3

14 CsEss Chapter 1.NET: What Is Really Happening The assembly that is created does not contain executable code, but, rather, code in Intermediate Language, or IL (sometimes called Microsoft Intermediate Language, or MSIL). In the Windows environment, this IL code is packaged up in a standard portable executable (PE) file format, so you will see the familiar.exe extension (or, if you are building a component, the.dll extension). You can view an assembly using the ILDASM tool. When you run the.exe, a special runtime environment (the Common Language Runtime, or CLR) is launched and the IL instructions are executed by the CLR. Unlike some runtimes, where the IL would be interpreted each time it is executed, the CLR comes with a just-in-time (JIT) compiler, which translates the IL to native machine code the first time it is encountered. On subsequent calls, the code segment runs as native code. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 4

15 CsEss Chapter 1.NET Programming in a Nutshell 1. Write your program in a high-level.net language, such as C#. 2. Compile your program into IL. 3. Run your IL program, which will launch the CLR to execute your IL, using its JIT to translate your program to native code as it executes. We will look at a simple example of a C# program, and run it under.net. Don t worry about the syntax of C#, which we will start discussing in the next chapter. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 5

16 CsEss Chapter 1.NET Program Example See SimpleCalc in the Chap01 folder. 1. Enter the program in a text editor. // SimpleCalc.cs // // This program does a simple calculation: // calculate area of a rectangle public class SimpleCalc { static void Main() { int width = 20; int height = 5; int area; area = width * height; System.Console.WriteLine("area = {0}", area); } } 2. Compile the program at the command-line. Start the console window via Start All Programs Microsoft Visual Studio 2012 Visual Studio Tools Developer Command Prompt for VS2012. Navigate to folder \OIC\CsEss\Chap01\SimpleCalc. >csc SimpleCalc.cs 3. Run your IL program SimpleCalc.exe >SimpleCalc area = 100 Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 6

17 CsEss Chapter 1 Viewing the Assembly You can view the assembly using the ILDASM tool 1. >ildasm SimpleCalc.exe 1 You can change the font size from the View menu. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 7

18 CsEss Chapter 1 Viewing Intermediate Language Double-click on Main:void() Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 8

19 CsEss Chapter 1 Understanding.NET The nice thing about a high-level programming language is that you usually do not need to be concerned with the platform on which the program executes. You can work with the abstractions provided by the language and with functions provided by libraries. Your appreciation of the C# programming language and its potential for creating great applications will be richer if you have a general understanding of.net. After this course, we suggest you next study: Test-Driven Development (Unit Testing).NET Framework Using C# And then, depending on your interests: Data Access Windows Web ADO.NET Windows Forms ASP.NET XML Programming WPF ASP.NET MVC ASP.NET AJAX Silverlight WCF Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 9

20 CsEss Chapter 1 Visual Studio 2012 While it is possible to write C# programs using any text editor, and compile them with the command-line compiler, it is very tedious to program that way. An IDE makes the process of writing software much easier. An IDE provides convenience items, such as a syntaxhighlighting editor. An IDE reduces the tedium of keeping track of configurations, environment settings and file organizations. You may use Visual Studio 2012 throughout this course to create and compile your C# programs. Visual Studio 2012 is discussed in more detail in Appendix A. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 10

21 CsEss Chapter 1 Creating a Console Application We will now create a simple console application. Our program is the same simple calculator we created earlier that was compiled at the command line. 1. From the Visual Studio main menu, choose File New Project... This will bring up the New Project dialog. 2. Choose Visual C# and Console Application. 3. Leave.NET Framework 4.5 as the target framework. Leave checked Create directory for solution In the Name field, type SimpleCalcVs and for Location browse to C:\OIC\CsEss\Demos. Click OK. 2 Examples in later chapters frequently do not have a directory for solution. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 11

22 CsEss Chapter 1 Adding a C# File There will be a number of starter files. Expand properties and select the files AssemblyInfo.cs, App.config and Program.cs. Press the Delete key. We are now going to add a file SimpleCalc.cs, which contains the text of our program. 1. In Solution Explorer, right click over SimpleCalcVs and choose Add New Item... This will bring up the Add New Item dialog. 2. In the middle pane, choose Code File. For Name type SimpleCalc.cs. Click Add. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 12

23 CsEss Chapter 1 Using the Visual Studio Text Editor The empty file SimpleCalc.cs will now be open in the Visual Studio text editor. Enter the following program. Or you could just copy from Chap01\SimpleCalc\. // SimpleCalc.cs // // This program does a simple calculation: // calculate area of a rectangle public class SimpleCalc { static void Main() { int width = 20; int height = 5; int area; area = width * height; System.Console.WriteLine("area = {0}", area); } } Notice that the Visual Studio text editor highlights syntax, indents automatically, and so on. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 13

24 CsEss Chapter 1 IntelliSense A powerful feature of Visual Studio is IntelliSense. IntelliSense will automatically pop up a list box allowing you to easily insert language elements directly into your code. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 14

25 CsEss Chapter 1 Build and Run the Project Building a project means compiling the individual source files and linking them together with any library files to create an IL executable.exe file. You can build the project by using one of the following: Menu Build Build Solution or toolbar button keyboard shortcut Ctrl+Shift+B. or Menu Build Build SimpleCalcVs or toolbar button just builds the project SimpleCalcVs) 3. (this You can run the program without the debugger by using one of the following: Menu Debug Start Without Debugging Toolbar button (This button is not provided by default; see Appendix A for how to add it to your Build toolbar.) Keyboard shortcut Ctrl + F5 You can run the program in the debugger by using one of the following: Menu Debug Start Debugging Toolbar button Keyboard shortcut F5. 3 The two are the same in this case, because the solution has only one project, but some solutions have multiple projects, and then there is a difference. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 15

26 CsEss Chapter 1 Pausing the Output If you run the program in the debugger from Visual Studio, you will notice that the output window automatically closes on program termination. To keep the window open, you may prompt the user for some input. public class SimpleCalc { static void Main() { int width = 20; int height = 5; int area; area = width * height; System.Console.WriteLine("area = {0}", area); System.Console.WriteLine( "Prese Enter to exit"); System.Console.ReadLine(); } } This program is saved as a Visual Studio solution in Chap01\SimpleCalcVs 4. Remember that you can always make the console window stay open by running without the debugger via Ctrl + F5. 4 The solution can be opened in either Visual Studio 2010 or Visual Studio The project uses.net 4.0 and so will run on either.net 4.0 or.net 4.5. The same is true with Chap01\SimpleCalcGui. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 16

27 CsEss Chapter 1 Visual C# and GUI Programs Microsoft s implementation of the C# language, Visual C#, works very effectively in a GUI environment. Using Windows Forms, it is easy to create Windows GUI programs in C#. Example: See Chap01\SimpleCalcGui We will discuss GUI programming using C# in Chapter 6. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 17

28 CsEss Chapter 1.NET Documentation.NET Framework documentation is included with Visual Studio Use the menu Help View Help. Other menu choices let you add and remove content and to set a preference for launching in Browser or Help Viewer. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 18

29 CsEss Chapter 1 Summary As in other environments, with.net you write a program in a high-level language, compile to an executable (.EXE file), and run that.exe file. The.EXE file, called an assembly, contains Intermediate Language instructions. You can view an assembly through the ILDASM tool. Visual Studio 2012 is a powerful IDE that makes it easy to develop C# programs. With Visual Studio it is easy to create GUI programs using C#. You can access extensive.net Framework documentation through the Visual Studio help system. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 19

30 CsEss Chapter 1 Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 20

31 CsEss Chapter 6 Chapter 6 Introduction to Windows Forms Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 219

32 CsEss Chapter 6 Introduction to Windows Forms Objectives After completing this unit you will be able to: Use Visual Studio 2012 to implement a simple graphical user interface with Windows Forms and basic controls. Use partial classes to organize class code over multiple files. Explain the principles of event handling in Windows Forms and implement handlers for simple control events. Use a ListBox control to display a list of objects. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 220

33 CsEss Chapter 6 Creating a Windows Forms App It is easy to create a Windows Forms application using the Form Designer in Visual Studio This same Form Designer is also available for Visual Basic and Visual C Create a new C# project BankGui of type Windows Forms Application. The Location should be the Demos directory. Leave checked Create directory for solution. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 221

34 CsEss Chapter 6 Windows Forms Demo (Cont d) 2. From the toolbox, drag two labels, two textboxes, and two buttons to the form. Use the resizing handles to resize the form. 3. Enter property values for the form, textboxes and buttons: Name Form1 txtamount txtbalance cmddeposit cmdwithdraw Text Bank Account (blank) (blank) Deposit Withdraw 4. Add event handlers for the buttons by double-clicking on each button. 5. Add an event handler for the Form s Load event by doubleclicking over any empty area of the form. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 222

35 CsEss Chapter 6 Windows Forms Demo (Cont d) 6. Add the following code: public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void cmddeposit_click(object sender, EventArgs e) { int amount = Convert.ToInt32(txtAmount.Text); int balance = Convert.ToInt32(txtBalance.Text); balance += amount; txtbalance.text = Convert.ToString(balance); } private void cmdwithdraw_click(object sender, EventArgs e) { int amount = Convert.ToInt32(txtAmount.Text); int balance = Convert.ToInt32(txtBalance.Text); balance -= amount; txtbalance.text = Convert.ToString(balance); } } private void Form1_Load(object sender, EventArgs e) { txtamount.text = "25"; txtbalance.text = "100"; } Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 223

36 CsEss Chapter 6 Windows Forms Demo (Cont d) 7. Build and run the application. It should behave like a standard Windows application. The completed demo is in the BankGui\Step1 directory for this chapter. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 224

37 CsEss Chapter 6 Partial Classes In.NET 2.0 and higher, you can split the definition of a class over two or more source files. Use the partial keyword modifier. Code maintenance can be simplified for large classes. The Windows Form Designer generates partial classes. The boiler plate code generated by the Form Designer is kept in one file, which is not touched by the programmers. Code added by the programmer is maintained in another file. // Form1.Designer.cs namespace BankGui { partial class Form1 { /// <summary> /// Required designer variable. /// </summary>... // Form1.cs... namespace BankGui { public partial class Form1 : Form { public Form1() { InitializeComponent(); }... Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 225

38 CsEss Chapter 6 Windows Forms Event Handling GUI applications are event-driven, in which the application executes code in response to user events, such as clicking the mouse, choosing a menu item, etc. Each form or control has a predefined set of events. For example, every button has a Click event. Windows Forms uses the.net event model, which uses delegates to bind events to the methods that handle them. Windows Forms typically uses multi-cast delegates. A multi-cast delegate maintains a list of the methods it is bound to. When an event occurs in an application, the control raises the event by calling the delegate for that event. The delegate then calls all of the methods it is bound to. C# provides the overloaded += operator for adding a delegate to an event. this.cmddeposit.click += new System.EventHandler(this.cmdDeposit_Click); This code is in the wizard-generated file Form1.Designer.cs. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 226

39 CsEss Chapter 6 Add Events for a Control Every control has a primary event. You can add a handler for this event by double-clicking on the control in the Visual Studio Form Designer. We added a handler for the Deposit and Withdraw buttons in this way. You can add other events by selecting the in the Properties window and double-clicking on a selected event. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 227

40 CsEss Chapter 6 Events Documentation You can find all of the events associated with a class in the.net Framework Reference. This screen shot shows documentation for the FormClosing event of the Form class. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 228

41 CsEss Chapter 6 Closing a Form A form may be closed in a number of ways, such as by clicking the at the top-right, using the system menu at the top-left, pressing Alt+F4, and so on. In all cases, the FormClosing event will be fired, providing an opportunity to cancel the closing. Continuing our simple Bank Account form demo, add the following code to the handler of the FormClosing event. See BankGui\Step2. private void Form1_FormClosing(object sender, FormClosingEventArgs e) { DialogResult result = MessageBox.Show( "Do you really want to close?", "Bank Account", MessageBoxButtons.YesNo); if (result!= DialogResult.Yes) e.cancel = true; } The following dialog will be displayed: Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 229

42 CsEss Chapter 6 ListBox Control The.NET Framework provides a number of controls that you can use to display lists of items to the user. These controls also allow the user to select an item from the list, typically by clicking on the item to be selected. The simplest list control is the ListBox control. The collection Items maintains a collection of object references. There are methods such as Add(), Remove() and Clear(). The property SelectedItem gets or sets the currently selected item in the listbox. Perform a cast to get out an item of a particular type. The property SelectedIndex gets or sets the zero-based index of the currently selected item ( 1 if no item is selected). The event SelectedIndexChanged is fired when the user selects a new index. There are many more properties, methods, and events, which you can study from the documentation. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 230

43 CsEss Chapter 6 ListBox Example The program ListBoxDemo illustrates maintaining a list of strings in a listbox. private void cmdadd_click(object sender, EventArgs e) { listbox1.items.add(txtstring.text); } private void cmdremove_click(object sender, EventArgs e) { listbox1.items.remove(txtstring.text); } private void listbox1_selectedindexchanged( object sender, EventArgs e) { if (listbox1.selectedindex!= -1) txtstring.text = (string)listbox1.selecteditem; } Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 231

44 CsEss Chapter 6 Lab 6 A GUI for Acme In this lab, you will implement a GUI interface for the Acme customer management system implemented in Chapter 4. Detailed instructions are contained in the Lab 6 write-up at the end of the chapter. Suggested time: 60 minutes Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 232

45 CsEss Chapter 6 Summary With Visual Studio 2012, you can implement a simple graphical user interface with Windows Forms and basic controls. You can use partial classes to organize class code over multiple files. Windows Forms uses the.net event architecture to handle user interface events..net provides various list controls, such as ListBox, for displaying lists of objects. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 233

46 CsEss Chapter 6 Introduction Lab 6 A GUI for Acme In this lab, you will implement a GUI interface for the Acme customer management system implemented in Chapter 4. Suggested Time: 60 minutes Root Directory: OIC\CsEss Directories: Labs\Lab6 CaseStudy\Acme\Step2C CaseStudy\Acme\Step3 (do your work here) (previous version) (answer) Files: AcmeCms.cs Part A. Create the GUI and List Customers 1. Create a new Visual C# project of type Windows Forms Application AcmeGui located in Labs\Lab6. 2. Change the file name Form1.cs to AcmeCms.cs. Say yes to rename all references to the code element Form1. Thus the form class will now also be AcmeCms. 3. Change the Text property of the form to Acme Customer Management System. 4. Add controls to the form as shown: Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 234

47 CsEss Chapter 6 5. Make the names of the controls shown: txtid, txt address, txtfirstname, txtlastname, listcustomers, cmdregister, cmdunregister, cmdchange . 6. Copy the files Customer.cs and Test.cs from CaseStudy\Acme\Step2C to the working directory. Add the file Customer.cs to the project. (Test.cs will be a miscellaneous file that you can refer to as you migrate command-line client code to GUI client code.) 7. Add a private data member custs of type Customers to class AcmeCms. 8. Create a handler for the Load event in the AcmeCms class. Add code to instantiate a custs object. 9. From the file Test.cs, copy code to display the customer list by calling a helper method ShowCustomerArray, passing it the results of calling the GetCustomer method. 10. Implement a private method ShowCustomerArray to display the customers in the array list in the list box of the main form. Base your code on the code in Test.cs. Don t worry about padding to make neat columns, because it won t work anyway in a listbox with a variable pitch font. (To make neat columns you should use a more advanced control, such as ListView or DataGridView.) Just use a single space as a separator of fields when you build up a string to add to the listbox. To add a string to a listbox, you can use the following code: listcustomers.items.add(str); If the array list is null, throw an exception. 11. Build and test the program. You should see a starting list of customers displayed. Part B. Register a New Customer In this part, you will add code for registering a new customer. 1. Add an event handler for clicking the Register button. 2. Add code in this handler to call the RegisterCustomer method of the Customers class. You will pass in the first name, last name, and address from the textboxes. You will get back an ID, which you will display. 3. Add code to redisplay all of the customers in the listbox. Build and test. 4. You will see the new customer that was added, but you will also see a duplicate of the original customers. Fix this problem by clearing the listbox in the helper method before doing the display. Build and test. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 235

48 CsEss Chapter 6 Part C. Select a Customer and Split into Fields In this part, you will add code to select a customer by clicking in the listbox. Relying on the specification that there are no embedded spaces in any of the fields of a customer, you will extract the individual fields using a space as a separator. This extracted information will be shown in the textboxes. 1. Add a handler for the event SelectedIndexChanged of the listbox. (Recall that you use the button to obtain a list of events associated with a control.) 2. Test to see if an item has been selected by checking if listcustomers.selectedindex is different from If an item has been selected, obtain the selected string and split it into fields (relying on a space as a separator) by the following code: string selected = (string) listcustomers.selecteditem; char[] sep = new char[] {' '}; string[] fields; fields = selected.split(sep); 5. Add code to set the textboxes to the corresponding fields of the selected customer. 6. Build and test. As you select different customers, you should see the information in the textboxes change appropriately. Part D. Unregister a Customer and Change Address In this final part, you will add code for unregistering a new customer. You will also add code for changing an address. 1. Add a handler for the Unregister button. 2. Add code to unregister the currently selected customer (if there is one), as shown by the ID. When done, clear the textboxes and refresh the listbox. You may build and test at this point. 3. Add a handler for the Change button. Add code to change the address of the currently selected customer (if there is one). 4. Build and test. Your miniature customer management system should now be fully operational! You are now at Step 3. Rev. 4.5 Copyright 2012 Object Innovations Enterprises, LLC 236