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tdelete
Deletes a specified node from a binary search tree.
Syntax
#include <search.h>
void *tdelete (void *key, void **rootp, int (*compar)());
Parameters
key A pointer to an item to be searched for and deleted.
rootp A pointer to the variable at the root of the tree.
compar A pointer to a comparison function supplied by the user.
Return Values
x A pointer to the parent node of the deleted entry.
NULL Entry not found or rootp is NULL on entry.
Description
The tdelete function searches a binary search tree for the specified
entry and deletes it if found. The tree is composed only of pointers.
The values reference by these pointers are stored separately from the
tree by the calling program.
The tdelete, tfind, tsearch, and twalk functions manage binary search
trees generalized from Knuth Algorithms T and D (6.2.2 ) described in The
Art of Computer Programming, Vol3 (Sorting and Searching) by Donald Ervin
Knuth (Reading, Mass.:Addison-Wesley, 1973).
If there is an item in the tree equal to *key (the value pointed to by
key), the pointer to the item is removed from the tree and the
descendants of that node are resorted. If no matching item is found in
the tree, a null pointer is returned.
If the deleted node is the root of the tree, the variable pointed to by
rootp is changed. A null value for the variable pointed to by rootp
indicates an empty tree.
The pointers to the key and the root of the tree should be of type
pointer-to- element, and cast to type pointer-to-character. Similarly,
although declared as type pointer-to-character, the value returned should
be cast into type pointer-to-element.
All comparisons are done with the function compar, which must be supplied
by the programmer. This function is called with two arguments, the
pointers to the elements being compared. The comparison function does
not need to compare every byte, so arbitrary data can be contained in the
elements in addition to the values being compared.
The comparison function should return an integer either less than, equal
to, or greater than zero, according to whether the first argument is to
be considered less than, equal to, or greater than the second argument.
If the calling function alters the pointer to the root, results are
unpredictable.
NOTE The tdelete function and the header file <search.h> are not part of
ANSI C. Using them may make your program less portable.
Examples
Refer to the example located in the tsearch() function description.
See Also
tfind(), tsearch(), twalk()