BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / stdlib / qsort.3

diff --git a/usr/src/lib/libc/stdlib/qsort.3 b/usr/src/lib/libc/stdlib/qsort.3
index 132571b..03f1b8d 100644 (file)
--- a/usr/src/lib/libc/stdlib/qsort.3
+++ b/usr/src/lib/libc/stdlib/qsort.3
@@ -1,78 +1,168 @@
-.\" Copyright (c) 1990 The Regents of the University of California.
+.\" Copyright (c) 1990, 1991 The Regents of the University of California.

 .\" All rights reserved.
 .\"
 .\" All rights reserved.
 .\"

-.\" %sccs.include.redist.man%
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.

 .\"
 .\"

-.\"    @(#)qsort.3     6.4 (Berkeley) %G%
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.

 .\"
 .\"

-.TH QSORT 3  ""
-.UC 4
-.SH NAME
-qsort \- quicker sort
-.SH SYNOPSIS
-.nf
-.ft B
-#include <stdlib.h>
-
-void
-qsort(void *base, size_t nmemb, size_t size,
-.RS
-.\" have to reset bold font
-.ft B
-int (*compar)(const void *, const void *));
-.RE
-.ft R
-.fi
-.SH DESCRIPTION
-.I Qsort
-is a modified partition-exchange sort, or quicksort.
-.PP
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     @(#)qsort.3    6.7 (Berkeley) 6/29/91
+.\"
+.Dd June 29, 1991
+.Dt QSORT 3
+.Os
+.Sh NAME
+.Nm qsort, heapsort
+.Nd sort functions
+.Sh SYNOPSIS
+.Fd #include <stdlib.h>
+.Ft void
+.Fn qsort "void *base" "size_t nmemb" "size_t size" "int (*compar)(const void *, const void *)"
+.Ft int
+.Fn heapsort "void *base" "size_t nmemb" "size_t size" "int (*compar)(const void *, const void *)"
+.Sh DESCRIPTION
+The
+.Fn qsort
+function is a modified partition-exchange sort, or quicksort.

 The
 The

-.I qsort 
-function sorts an array of
-.I nmemb
+.Fn heapsort
+function is a modified selection sort.
+.Pp
+The
+.Fn qsort
+and
+.Fn heapsort
+functions sort an array of
+.Fa nmemb

 objects, the initial member of which is pointed to by
 objects, the initial member of which is pointed to by

-.IR base .
+.Fa base .

 The size of each object is specified by
 The size of each object is specified by

-.IR size .
-.PP
+.Fa size .
+.Pp

 The contents of the array are sorted in ascending order according to
 a comparison function pointed to by
 The contents of the array are sorted in ascending order according to
 a comparison function pointed to by

-.IR compar ,
+.Fa compar ,

 which is called with two arguments that point to the objects being
 compared.
 which is called with two arguments that point to the objects being
 compared.

-.PP
+.Pp

 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.
 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.

-.PP
-.I Qsort
-is
-.B not
+.Pp
+The functions
+.Fn qsort
+and
+.Fn heapsort
+are
+.Em not

 stable, that is, if two members compare as equal, their order in
 the sorted array is undefined.
 stable, that is, if two members compare as equal, their order in
 the sorted array is undefined.

-.PP
-.I Qsort
-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.
-.I Qsort
+.Pp
+The
+.Fn qsort
+function 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.
+.Fn Qsort

 takes O N lg N average time.
 takes O N lg N average time.

-.SH "RETURN VALUES"
-.I Qsort 
+This implementation uses median selection to avoid the traditional
+O N**2 worst-case behavior.
+.Pp
+The
+.Fn heapsort
+function is an implementation of J.W.J. William's ``heapsort'' algorithm,
+a variant of selection sorting; in particular, see D.E. Knuth's Algorithm H.
+.Fn Heapsort
+takes O N lg N worst-case time.
+Its
+.Em only
+advantage over
+.Fn qsort
+is that it uses no additional memory.
+.Sh RETURN VALUES
+The
+.Fn qsort
+function

 returns no value.
 returns no value.

-.SH COMPATIBILITY
+.Pp
+Upon successful completion,
+.Fn heapsort
+returns 0.
+Otherwise, it returns \-1 and the global variable
+.Va errno
+is set to indicate the error.
+.Sh ERRORS
+The
+.Fn heapsort
+function succeeds unless:
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The
+.Fa size
+argument is zero.
+.Sh COMPATIBILITY

 Previous versions of
 Previous versions of

-.I qsort
+.Fn qsort

 did not permit the comparison routine to itself call
 did not permit the comparison routine to itself call

-.IR qsort (3).
+.Fn qsort 3 .

 This is no longer true.
 This is no longer true.

-.SH "SEE ALSO"
-sort(1), radixsort(3)
-.sp
-Hoare, C.A.R. [1962]. "Quicksort", The Computer Journal, 5:1, pp. 10-15.
-.br
-Knuth, D.E. [1968]. "The Art of Computer Programming Vol. 3: Sorting and
-Searching", pp. 114-123.
-.SH STANDARDS
-.I Qsort
-conforms to ANSI X3.159-1989 (``ANSI C'').
+.Sh SEE ALSO
+.Xr sort 1 ,
+.Xr radixsort 3
+.Rs
+.%A Hoare, C.A.R.
+.%D 1962
+.%T "Quicksort"
+.%J "The Computer Journal"
+.%V 5:1
+.%P pp. 10-15
+.Re
+.Rs
+.%A Williams, J.W.J
+.%D 1964
+.%T "Heapsort"
+.%J "Communications of the ACM"
+.%V 7:1
+.%P pp. 347-348
+.Re
+.Rs
+.%A Knuth, D.E.
+.%D 1968
+.%B "The Art of Computer Programming"
+.%V Vol. 3
+.%T "Sorting and Searching"
+.%P pp. 114-123, 145-149
+.Re
+.Sh STANDARDS
+The
+.Fn qsort
+function
+conforms to
+.St -ansiC .