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

238 Chapter5
HP C/iX Library Function Descriptions
lsearch
lsearch
Performs a linear search and update.
Syntax
#include <stdio.h>
#include <search.h>
char *lsearch ((char *) key , (char *) base , nelp ,
sizeof(* key ), compar )
unsigned * nelp ;
int (* compar )( );
Parameters
key A pointer to the value to be found in the table.
base A pointer to the first element in the table.
nelp A pointer to an integer containing the current number of elements in the
table. This integer is incremented if the item is added to the table.
width The width of each table row.
compar A pointer to a comparison function that you must supply, such as strcmp.
It is called with two arguments that point to the elements being compared.
The function must return zero if the elements are equal, and nonzero if
they are not equal.
Return Values
x A character pointer to the element being sought, whether newly added or
pre-existing in the table.
Description
The lsearch function is a linear search function generalized from Knuth Algoritm S (6.1).
1
It returns a pointer into a table indicating where an item may be found. If the item does
not occur, it is added at the end of the table.
The pointers to the key and the element at the base of the table should be of type
pointer-to-element, and cast to type pointer-to-character.
The comparison function does not need to compare every byte, so arbitrary data may be
contained in the elements in addition to the values being compared.
The value returned is declared as type pointer-to-character, but should be cast as type
1. The Art of Computer Programming, Vol.3 (Sorting and Searching) by Donald Ervin Knuth (Reading,
Mass:Addison-Wesley, 1973).