#include <stdlib.h>(See libbsd(7) for include usage.)
radixsort(const unsigned char **base, int nmemb, const unsigned char *table, unsigned endbyte);
unsigned char **base, int
nmemb, const unsigned
char *table, unsigned
sradixsort() functions are implementations of radix sort.
These functions sort an nmemb element array of pointers to byte strings, with the initial member of which is referenced by base. The byte strings may contain any values. End of strings is denoted by character which has same weight as user specified value endbyte. endbyte has to be between 0 and 255.
Applications may specify a sort order by providing the
table argument. If non-
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.
sradixsort() function is stable, that
is, if two elements compare as equal, their order in the sorted array is
sradixsort() function uses additional
memory sufficient to hold nmemb pointers.
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.
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.
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.
radixsort() function first appeared in 4.4BSD.
|January 27, 1994||Linux 4.19.0-6-amd64|