radixsort, sradixsort - radix sort
radixsort(const u_char **base, int nmemb, const u_char
sradixsort(const u_char **base, int nmemb, const u_char
The radixsort() and sradixsort() functions are implementations of radix
These functions sort an array of nmemb pointers to byte
initial member is referenced by base. The byte strings may
values; the end of each string is denoted by the user-specified value
Applications may specify a sort order by providing the table
If non-null, table must reference an array of UCHAR_MAX + 1
contains the sort weight of each possible byte value. The
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
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,
of the array are sorted in ascending order according to the
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
function uses additional memory sufficient to hold nmemb
The radixsort() function is not stable, but uses no additional memory.
These functions are variants of most-significant-byte radix
particular, see D.E. Knuth's Algorithm R and section 5.2.5,
They take linear time relative to the number of bytes in the
Upon successful completion 0 is returned. Otherwise, -1 is
the global variable errno is set to indicate the error.
[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).
Knuth, D.E., "Sorting and Searching", The Art of Computer
Vol. 3, pp. 170-178, 1968.
Paige, R., "Three Partition Refinement Algorithms", SIAM J.
6, Vol. 16, 1987.
McIlroy, P., "Computing Systems", Engineering Radix Sort,
Vol. 6:1, pp.
The radixsort() function first appeared in 4.4BSD.
OpenBSD 3.6 January 27, 1994
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