Copyright (c) 1990 The Regents of the University of California.
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%sccs.include.redist.man%

@(#)radixsort.3 5.4 (Berkeley) 11/21/90

radixsort - radix sort

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

radixsort(u_char **base, int nmemb, u_char *table, u_char endbyte);

Radixsort is a modified radix sort.

The radixsort function sorts an array of nmemb 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 . The contents of the array are sorted in ascending order according to the ASCII order of the byte strings they reference.

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. More than one byte may have the same sort weight. 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.

Radixsort is stable, that is, if two elements compare as equal, their order in the sorted array is unchanged.

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. Radixsort takes linear time relative to the number of bytes in the strings.

sort(1), qsort(3) Knuth, D.E. [1968]. "The Art of Computer Programming Vol. 3: Sorting and Searching", pp. 170-178.

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

Upon successful completion 0 is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error. Radixsort may fail and set errno for any of the errors specified for the library routine malloc (3). Nmemb must be less than the maximum integer, INT_MAX.