vb.net barcode reader code Part II Designing Types in C#.net

Create PDF 417 in C#.net Part II Designing Types

Another solution that you can implement uses the session s context_info . Logically, context_ info is a VARBINARY(128) variable owned by the session . At any point in the session, you can change it by using the SET CONTEXT_INFO command or query it by using the CONTEXT_ INFO function . You can rely on the session s context_info to communicate between different levels of code in our case, between the calling batch and the trigger . Think of context_info as a global session variable . For example, a batch can store a specific GUID in a section of the session s context_info when it wants to send a signal to the trigger . The trigger will look for that particular GUID to determine whether or not to continue running the code . To generate the GUID that you will use as your signal, you can use the NEWID function, as in:

4. Review your date and time settings. After selecting your time zone, check the date and time carefully. Incorrect values in either of these settings can cause complications later.

these situations can allow nefarious individuals to access information that should not leave the organization. Computers might be missing updates because they have been turned off for an extended period of time, or if they were unable to connect to the network for some reason. They could become misconfigured if users have more privileges on their systems than best practices prescribe. They could become infected with malicious software because the user accessed dangerous Web sites or opened files infected with a virus.

If you re connected to the internet and you ve accepted the default settings for Windows Media Player, the Player automatically downloads information about the CD you re currently playing, including the album cover, track names, and information about the artists and composers on the CD. For more information, right-click the album cover and click Find Album Info; this displays the dialog box shown in Figure 16-3. To read a bio of the artist or group and a review of the album, click the Buy CDs link, which opens your default web browser and takes you to a Microsoft-operated shopping site.

1 The CLR s Execution Model C# source code file(s) Basic source code file(s) IL source code file(s)

Now when a new Rectangle is constructed, what do you think the x and y fields in the two Point fields, topLeft and bottomRight, would be initialized to: 0 or 5 (Hint: This is trick question.) Many developers (especially those with a C++ background) would expect the C# compiler to emit code in Rectangle s constructor that automatically calls Point s default parameterless constructor for the Rectangle s two fields. However, to improve the run time performance of the application, the C# compiler doesn t automatically emit this code. In fact, many compilers will never emit code to call a value type s default constructor automatically, even if the value type offers a parameterless constructor. To have a value type s parameterless constructor execute, the developer must add explicit code to call a value type s constructor. Based on the information in the preceding paragraph, you should expect the x and y fields in Rectangle s two Point fields to be initialized to 0 in the code shown earlier because there are no explicit calls to Point s constructor anywhere in the code. However, I did say that my original question was a trick question. The trick part is that C# doesn t allow a value type to define a parameterless constructor. So the previous code won t actually compile. The C# compiler produces the following error when attempting to compile that code: error CS0568: Structs cannot contain explicit parameterless constructors. C# purposely disallows value types to define parameterless constructors to remove any confusion a developer might have about when that constructor gets called. If the constructor can t be defined, the compiler can never generate code to call it automatically. Without a parameterless constructor, a value type s fields are always initialized to 0/null.

Page xvi Acknowledgements Written by: Matt Lichtenberg and Jim Travis Reviewed and revised by: Bill Birney and Mark Galioto Project managed by: Terrence Dorsey, Seth McEvoy, and Tom Woolums Edited by: Terrence Dorsey and Kari Rosenthal Annand Illustrations and production by: Greg Lovitt Indexed by: Terrence Dorsey and Cathy McDonald Companion CD produced by: C. Keith Gabbert and Kari Rosenthal Annand Sample CD content provided by: Gary Schare and Ellen Wechsler Technical content reviewed by: Matthew Clapham, Eric Juteau, May Lau, Mike Matsel, J.P. McKinney, Ian Mercer, R. Cutts Peaslee, James Peters, Jen Rowe, Ellen Wechsler, and Kristen Whalen. Legal review by: Debbie Donaty Marketing information provided by: Marcus Matthias Additional editorial assistance provided by: Bill Birney, Karl Erickson, Gregory Finch, John Shaw, and Tom Woolums. Companion CD additional contributors: Henry Bale and Robert L. Porter Special thanks to Microsoft Press editors: Alex Blanton and Aileen Wrothwell System Requirements Use the following information to make sure your computer is compatible with Microsoft Producer and the content provided on the companion CD. Microsoft Producer for PowerPoint 2002 Microsoft Producer requires the following minimum system requirements: Microsoft Windows 2000 with Service Pack 1 or Microsoft Windows XP operating system. 400 megahertz (MHz) processor. A processor speed of 600 MHz or higher is recommended when capturing from a digital video device. 128 megabytes (MB) of RAM. 2 gigabytes (GB) of free hard disk space.

The SQL Worksheet is where you enter commands to query and modify data. Like SQL*Plus, you can enter SQL and PL/SQL commands. Some SQL*Plus commands are supported, such as COLUMN, DESCRIBE and SPOOL. For a full list of supported and unsupported SQL*Plus commands, please refer to the Oracle SQL Developers User s Guide. The Worksheet is automatically opened when you connect to a database. If you need to open another worksheet or have closed the only one open, click on the SQL Worksheet icon or select the Tools SQL Worksheet menu option.

For this task, you should complete Practices 1 and 2. Complete Practice 3 to obtain extra experience with the CustomValidator control.

To remove a tab, click the tab to select it and click the Remove button on the Home tab in the ribbon. Sections In each tab, you can group information in sections. In Figure 7-2, Professional Information and Billing Information are sections on the Details tab. A default section is created in each column when you add a tab to a form. The steps to create a section are similar to those used to create a tab. In the form editor, select the tab to which you want to add the section, click the Insert tab in the ribbon, and then click the button with the number of columns you want in your section in the ribbon s Section area.