how to create barcode in vb.net 2012 Figure 2-5. Choosing the .NET Framework version in visual basic

Maker barcode data matrix in visual basic Figure 2-5. Choosing the .NET Framework version

Figure 5-8. Selecting the OrderItem class For this project, you ll simply charge a fixed amount for all items. In a real scenario, you would probably look up the item properties from a database. For now, however, drag an Assign activity onto the ForEach activity.

Let s look at an example of when you might need to mount a drive manually. Suppose that you ve just added a second hard disk to your PC that has previously been used on a Windows system, and you want to salvage some data before formatting the disk. Let s also assume the new disk has been added as the slave on the primary IDE channel, which is the usual method of adding a second disk to an IDE-based computer.

Another important data type that often should be passed to native code is a function pointer. Function pointers are widely used to implement callbacks and provide a simple form of functional programming; think for instance of a sort function that receives as input the pointer to the comparison function. Graphical toolkits have widely used this data type to implement event-driven programming, and they often have to pass a function that is invoked by another one. PInvoke can marshal delegates as function pointers; again, the runtime is responsible for generating a suitable function pointer callable from native code. When the marshalled function pointer is invoked, a stub is called, and the activation record on the stack is rearranged to be compatible with the calling convention of the runtime. Then, the delegate function is invoked. Although in principle the generated stub is responsible for implementing the calling convention adopted by the native code receiving the function pointer, the CLR supports only the stdcall calling convention for marshalling function pointers. Thus, the native code should adopt this calling convention when invoking the pointer; this restriction may cause problems, but in general on the Windows platform the stdcall calling convention is widely used. The following C function uses a function pointer to apply a function to an array of integers: typedef int (CALLBACK *TRANSFORM_CALLBACK)(int); void CINTEROPDLL_API transformArray(int* data, int count, TRANSFORM_CALLBACK fn) { int i; for (i = 0; i < count; i++) data[i] = fn(data[i]); } The TRANSFORM_CALLBACK type definition defines the prototype of the function pointer you re interested in here: a function taking an integer as the input argument and returning an integer as a result. The CALLBACK macro is specific to the Microsoft Visual C++ compiler and expands to __stdcall in order to indicate that the function pointer, when invoked, should adopt the stdcall calling convention instead of the cdecl calling convention. The transformArray function takes as input an array of integers with its length and the function to apply to its elements. You now have to define the F# prototype for this function by introducing a delegate type with the same signature as TRANSFORM_CALLBACK: type Callback = delegate of int -> int [<DllImport("CInteropDLL", CallingConvention=CallingConvention.Cdecl)>] extern void transformArray(int[] data, int count, Callback transform); Now, you can increment all the elements of an array by using the C function: let data = [| 1; 2; 3 |] printf "%s\n" (string.Join("; ", (Array.map any_to_string data))) CInterop.transformArray(data, data.Length, new CInterop.Callback(fun x -> x + 1)) printf "%s\n" (string.Join("; ", (Array.map any_to_string data)))

Note For compatibility with OCaml, the ^ operator can also be used for string concatenation, although it s

3 discussed how BlackBerry devices offer a range of codecs to play back audio and video content. This appendix provides some more details on codec support for a range of popular BlackBerry devices. Please see Table A-1 for this information. Notes applying to each device/codec combination follow the table.

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