.\" Copyright (c) 1990 The Regents of the University of California.
.\" %sccs.include.redist.man%
.\" @(#)qsort.3 6.4 (Berkeley) %G%
qsort(void *base, size_t nmemb, size_t size,
.\" have to reset bold font
int (*compar)(const void *, const void *));
is a modified partition-exchange sort, or quicksort.
function sorts an array of
objects, the initial member of which is pointed to by
The size of each object is specified by
The contents of the array are sorted in ascending order according to
a comparison function pointed to by
which is called with two arguments that point to the objects being
The comparison function must return an integer less than, equal to, or
greater than zero if the first argument is considered to be respectively
less than, equal to, or greater than the second.
stable, that is, if two members compare as equal, their order in
the sorted array is undefined.
is an implementation of C.A.R. Hoare's ``quicksort'' algorithm, a variant
of partition-exchange sorting; in particular, see D.E. Knuth's Algorithm Q.
takes O N lg N average time.
did not permit the comparison routine to itself call
Hoare, C.A.R. [1962]. "Quicksort", The Computer Journal, 5:1, pp. 10-15.
Knuth, D.E. [1968]. "The Art of Computer Programming Vol. 3: Sorting and
conforms to ANSI X3.159-1989 (``ANSI C'').