Programming Visual Basic for the Palm OS

Data Formats

Until now, our focus has been on how to interface with the HotSync manager, and how to use the Sync Suite API to synchronize databases and records. It was easy to read and write the actual record data, because we only supported ASCII strings. A real Palm program is going to have a much more complicated record structure, with a mixture of string and binary data.

The sample code for this section includes a new AppForge project, Ch4b.vbp., and a new conduit project, Ch4bCond.vbp. Together, these show how to handle the low-level chores associated with packing and unpacking record data, converting numbers between the Intel and Motorola formats, and handling differences between Palm and Windows date formats.

Note that if you use the AppForge database utilities and the Universal Conduit, you don’t have to worry about packing and unpacking records and fields, or converting between Palm PDA and Windows data types. We covered the database utilities in Chapter 3, and will look at the Universal Conduit in Chapter 5.

Creating Packed Record Data

Our new application creates a database that consists of structured records with four fields: a Date value, a Time value, a Boolean value, an Integer value, a Long integer, and a String with 20 characters. Figure 4-9 shows the application’s user interface on the Palm PDA.

Figure 4-9. Mains screen for sample application Ch4b

First, let’s look ...