vb.net barcode scanner source code Part IV in visual C#.net

Printing PDF 417 in visual C#.net Part IV

I want to upload a custom icon, so I expand the Upload section at the bottom of the window and click the Browse button (see Figure 4-19). I select my houseicon.png file and click the Upload button. A thumbnail of the new graphic automatically appears in the images contact sheet.

As you can see, this class encapsulates the notion of a value type that can also be null . Since Nullable<T> is itself a value type, instances of it are still fairly lightweight . That is, instances can still be on the stack, and an instance is the same size as the original value type plus the size of a Boolean field . Notice that Nullable s type parameter, T, is constrained to struct . This was done because reference type variables can already be null .

Configuring TCP/IP Settings for DNS Clients . . . . . . . . . . . . . . . . . . . . . . . 4-53

5. Write down the eight-digit key displayed on the screen and return to the old computer. 6. Follow the wizard s prompts, choosing the New Transfer operation, and specify that you plan to use the network to transfer files. When you reach the Do You Have a Windows Easy Transfer Key screen, click Yes, I Have a Key. On the following page enter the key from the other computer. 7. When Windows confirms that you ve successfully made a connection, return to the old computer and choose which files to transfer.

arrid ---------A A A A A B B B C C C C C C C C C C D D D D value ------------20 223 2544 25567 14 30 -23433 28 12 10 8099 12 1200 13 12 14 10 9 -4 -6 -45678 -2

Suppose that this page also contains a button with an event that captures the selected item from the DropDownList and displays it on a label. This button control s event code might look as follows.

page_185

<EmployeeID>991</EmployeeID> <FirstName>Dino</FirstName> <LastName>Esposito</LastName> <City>Roma</City> <Territory TerritoryID="1" /> <Territory TerritoryID="2" /> </Employees> <Employees> <EmployeeID>992</EmployeeID> <FirstName>Francesco</FirstName> <LastName>Esposito</LastName> <City>Roma</City> <Territory TerritoryID="5" /> </Employees> </ROOT> The schema that would make it possible for the bulk loader to interpret and process this information is shown here: <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sql="urn:schemas-microsoft-com:mapping-schema"> <xsd:annotation> <xsd:appinfo> <sql:relationship name="Employees2Territories" parent="Employees" parent-key="EmployeeID" child="EmployeeTerritories" child-key="EmployeeID" /> </xsd:appinfo> </xsd:annotation> <xsd:element name="Employees" sql:relation="Employees" > <xsd:complexType> <xsd:sequence> <xsd:element name="EmployeeID" type="xsd:int" /> <xsd:element name="FirstName" type="xsd:string" /> <xsd:element name="LastName" type="xsd:string" /> <xsd:element name="City" type="xsd:string" /> <xsd:element name="Territory" sql:relation="EmployeeTerritories" sql:relationship="Employees2Territories" > <xsd:complexType> /> <xsd:attribute name="TerritoryID" 309 type="xsd:integer"

As you can see, the AttributeUsageAttribute type has a constructor that allows you to pass bit flags indicating where your attribute can legally be applied. The System.AttributeTargets enumerated type is defined in the FCL as follows:

Now when you run your application and type an invalid value in the TextBox, you ll see that it is converted to 0 and bound correctly.

Note To write this query, you have to know the names of the attributes. If you don t, you ll need to construct the query string dynamically. I ll provide an example later in the chapter. This technique for pivoting data is very ef cient because it scans the base table only once. SQL Server supports a native specialized table operator for pivoting called PIVOT. This operator does not provide any special advantages over the technique I just showed, except that it allows for shorter code. It doesn t support dynamic pivoting, and underneath the covers, it applies very similar logic to the one I presented in the last solution. So you probably won t even nd noticeable performance differences. At any rate, here s how you would pivot the OpenSchema data using the PIVOT operator:

Cascade None (referential)

12:

Unfortunately, there are two problems with the code above: