HP C/iX Library Reference Manual (30026-90004)

Chapter 5 211
HP C/iX Library Function Descriptions
hsearch
hsearch
Returns a pointer into a hash table, indicating the location of a specified entry.
Syntax
#include <search.h>
ENTRY *hsearch (ENTRY item , ACTION action );
Parameters
item A structure of type ENTRY, defined in the <search.h> header file. The item
parameter contains two pointers:
•
item. key points to the comparison key.
•
item. data points to any other data to be associated with that key.
Pointers to types other than character should be cast to
pointer-to-character.
action A member of an enumeration type ACTION which indicates the disposition
of the entry if it cannot be found in the table. ENTER indicates that the item
should be inserted in the table at an appropriate point. FIND indicates that
no entry should be made. Unsuccessful resolution is indicated by the
return of a null pointer.
Return Values
x A pointer to an object of type ENTRY, giving the location of the item in the
table.
NULL The table is full, or the item was not found.
Description
The hsearch function returns a pointer into a hash table, indicating the location at which
a specified entry can be found. This function uses malloc() to allocate space.
Only one hash search table may be active at any given time. The hcreate function must be
called before hsearch() to allocate sufficient space for the hash table.
The hsearch function is a hash-table search function generalized from Knuth Algorithm D
(6.4) described in The Art of Computer Programming, Vol.3 (Sorting and Searching) by
Donald Ervin Knuth (Reading, Mass.:Addison- Wesley, 1973).
NOTE The hsearch function and the header file <search.h> are not part of ANSI C.
Using them may make your program less portable.