Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Contact Us
Online Help
Domain Status
Man Pages

Virtual Servers

Topology Map

Server Agreement
Year 2038

USA Flag



Man Pages
RADIXSORT(3) FreeBSD Library Functions Manual RADIXSORT(3)

radixsort, sradixsort
radix sort

Standard C Library (libc, -lc)

#include <limits.h>
#include <stdlib.h>
radixsort(const unsigned char **base, int nmemb, const unsigned char *table, unsigned endbyte);
sradixsort(const unsigned char **base, int nmemb, const unsigned char *table, unsigned endbyte);

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.

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.

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).

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.

The radixsort() function first appeared in 4.4BSD.
January 27, 1994 FreeBSD 12.0-RELEASE

Search for    or go to Top of page |  Section 3 |  Main Index

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with ManDoc.