HP-UX Reference (11i v2 03/08) - 3 Library Functions N-Z (vol 7)

qsort(3C) qsort(3C)

NAME

qsort( ) - quicksort

SYNOPSIS

#include <stdlib.h>

void qsort(

void *base,

size_t nel,

size_t size,

int (*compar)(const void *, const void *)

);

DESCRIPTION

qsort() is an implementation of the quicksort algorithm. It sorts a table of data in place.

base Pointer to the element at the base of the table.

nel Number of elements in the table.

size Size of each element in the table.

compar Name of the comparison function, which is called with two arguments that point to the

elements being compared. The function passed as compar must return an integer less

than, equal to, or greater than zero, according to whether its ﬁrst argument is to be

considered less than, equal to, or greater than the second.

strcmp() uses this same

return convention (see string (3C)).

NOTES

The pointer to the base of the table should be of type pointer-to-element, and cast to type pointer-to-void.

The comparison function need not compare every byte; thus, arbitrary data can be contained in the ele-

ments in addition to the values being compared.

The order in the output of two items which compare as equal is unpredictable.

WARNINGS

If size is zero, a divide-by-zero error might be generated.