usr/src/lib/libc/stdlib/radixsort.3

.\" Copyright (c) 1990 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" %sccs.include.redist.man%
.\"
.\"     @(#)radixsort.3 5.4 (Berkeley) %G%
.\"
.TH radixsort 3 ""
.SH NAME
radixsort \- radix sort
.SH SYNOPSIS
.nf
.ft B
#include <limits.h>
#include <stdlib.h>

radixsort(u_char **base, int nmemb, u_char *table, u_char endbyte);
.ft R
.fi
.SH DESCRIPTION
.I Radixsort
is a modified radix sort.
.PP
The
.I radixsort
function sorts an array of
.I nmemb
pointers to byte strings, the initial member of which is referenced
by
.IR base .
The byte strings may contain any values; the end of each string
is denoted by the user-specified value
.IR endbyte .
The contents of the array are sorted in ascending order according
to the ASCII order of the byte strings they reference.
.PP
Applications may specify a sort order by providing the
.IR table
argument.
If non-NULL,
.I table
must reference an array of UCHAR_MAX + 1 bytes which contains the sort
weight of each possible byte value.
The end-of-string byte must have a sort weight of 0.
More than one byte may have the same sort weight.
.I Table
is useful for applications which wish to sort different characters
equally; for example, providing a table with the same weights
for A-Z as for a-z will result in a case-insensitive sort.
.PP
.I Radixsort
is stable, that is, if two elements compare as equal, their order in
the sorted array is unchanged.
.PP
.I Radixsort
is a variant of most-significant-byte radix sorting; in particular, see
D.E. Knuth's Algorithm R and section 5.2.5, exercise 10.
.I Radixsort
takes linear time relative to the number of bytes in the strings.
.SH SEE ALSO
sort(1), qsort(3)
.sp
Knuth, D.E. [1968]. "The Art of Computer Programming Vol. 3:
Sorting and Searching", pp. 170-178.
.br
Paige, R. [1987]. "Three Partition Refinement Algorithms",
SIAM J. Comput. Vol. 16, No. 6.
.SH "RETURN VALUES"
Upon successful completion 0 is returned.
Otherwise, \-1 is returned and the global variable
.I errno
is set to indicate the error.
.SH ERRORS
.I Radixsort
may fail and set
.I errno
for any of the errors specified for the library routine
.IR malloc (3).
.SH BUGS
.I Nmemb
must be less than the maximum integer, INT_MAX.