RtlNumberGenericTableElements function

The RtlNumberGenericTableElements routine returns the number of elements in a generic table.


NTSYSAPI ULONG RtlNumberGenericTableElements(



Pointer to the generic table (RTL_GENERIC_TABLE). The table must have been initialized by calling RtlInitializeGenericTable.

Return Value

RtlNumberGenericTableElements returns the number of elements that are currently stored in the table.


Callers of the Rtl..GenericTable routines are responsible for exclusively synchronizing access to the generic table. An exclusive fast mutex is the most efficient synchronization mechanism to use for this purpose.

By default, the operating system uses splay trees to implement generic tables. Under some circumstances, operations on a splay tree will make the tree deep and narrow and might even turn it into a straight line. Very deep trees degrade the performance of searches. You can ensure a more balanced, shallower tree implementation of generic tables by using Adelson-Velsky/Landis (AVL) trees. If you want to configure the generic table routines to use AVL trees instead of splay trees in your driver, insert the following define statement in a common header file before including Ntddk.h:


If RTL_USE_AVL_TABLES is not defined, you must use the AVL form of the generic table routines. For example, use the RtlNumberGenericTableElementsAvl routine instead of RtlNumberGenericTableElements. In the call to RtlNumberGenericTableElementsAvl, the caller must pass a RTL_AVL_TABLE table structure rather than RTL_GENERIC_TABLE.

Callers of RtlNumberGenericTableElements must be running at IRQL < DISPATCH_LEVEL if the caller-allocated memory for the generic table is pageable.


Target Platform Universal
Header ntddk.h (include Ntddk.h, Ntifs.h)
Library NtosKrnl.lib
DLL NtosKrnl.exe
IRQL "< DISPATCH_LEVEL (see Remarks section)"

See Also