Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
RADIXSORT(3)	       FreeBSD Library Functions Manual		  RADIXSORT(3)

NAME
     radixsort,	sradixsort -- radix sort

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <limits.h>
     #include <stdlib.h>

     int
     radixsort(const unsigned char **base, int nmemb,
	 const unsigned	char *table, unsigned endbyte);

     int
     sradixsort(const unsigned char **base, int	nmemb,
	 const unsigned	char *table, unsigned endbyte);

DESCRIPTION
     The radixsort() and sradixsort() functions	are implementations of radix
     sort.

     These functions sort an array of pointers to byte strings,	the initial
     member of which is	referenced by base.  The byte strings may contain any
     values; the end of	each string is denoted by the user-specified value
     endbyte.

     Applications may specify a	sort order by providing	the table argument.
     If	non-NULL, 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 or 255 (for sorting in reverse order).
     More than one byte	may have the same sort weight.	The table argument 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.  If table is NULL,	the contents
     of	the array are sorted in	ascending order	according to the ASCII order
     of	the byte strings they reference	and endbyte has	a sorting weight of 0.

     The sradixsort() function is stable, that is, if two elements compare as
     equal, their order	in the sorted array is unchanged.  The sradixsort()
     function uses additional memory sufficient	to hold	nmemb pointers.

     The radixsort() function is not stable, but uses no additional memory.

     These functions are variants of most-significant-byte radix sorting; in
     particular, see D.E. Knuth's Algorithm R and section 5.2.5, exercise 10.
     They take linear time relative to the number of bytes in the strings.

RETURN VALUES
     The radixsort() function returns the value	0 if successful; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     [EINVAL]		The value of the endbyte element of table is not 0 or
			255.

     Additionally, the sradixsort() function may fail and set errno for	any of
     the errors	specified for the library routine malloc(3).

SEE ALSO
     sort(1), qsort(3)

     Knuth, D.E., "Sorting and Searching", The Art of Computer Programming,
     Vol. 3, pp. 170-178, 1968.

     Paige, R.,	"Three Partition Refinement Algorithms", SIAM J. Comput., No.
     6,	Vol. 16, 1987.

     McIlroy, P., "Computing Systems", Engineering Radix Sort, Vol. 6:1, pp.
     5-27, 1993.

HISTORY
     The radixsort() function first appeared in	4.4BSD.

FreeBSD	11.1		       January 27, 1994			  FreeBSD 11.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=radixsort&sektion=3&manpath=FreeBSD+11.1-RELEASE>

home | help