National Instruments 320682C DestroyXProperty

X Property Library Chapter 9

LabWindows/CVI Standard Libraries 9-12 © National Instruments Corporation

Parameter Discussion

Usually, you can use the expression sizeof(

) for the size parameter, where

is the

C data type (char, int, and others) used to store the property value. This value must be a

multiple of the unit argument.

unit specifies how the X server should view the property item (as an array of 1-byte, 2-byte or

4-byte objects) and is necessary to perform simple byte-swapping between different types of

computers. See the notes near the end of this function description.

If the property item consists of a single object, such as an integer or a character, the unit should

be just the size of the object. An exception is the double type, for which the default unit

should be 4 bytes.

If the property item is a structure or array containing a number of smaller objects, then the unit

should be the number of bytes in the smaller objects.

Note: If you are communicating with a remote X server on a computer that has different

byte-ordering than your application, the unit specified is used to perform the byte

swapping. However, byte swapping cannot be properly performed for structures

containing different size members or for double type. For these special cases, use a

unit of 1 and then explicitly perform byte swapping where needed.

Note: The LabWindows/CVI X Property Library specifies units in the number of BYTES as

opposed to BITS. Thus, the "format" values of 8, 16 and 32 used by Xlib functions

correspond to units of 1, 2 and 4, respectively in the functions of the LabWindows/CVI

X Property Library.