# radixsort (3) - Linux Man Pages

## radixsort: radix sort

## NAME

**radixsort**
**sradixsort**
- radix sort

## LIBRARY

Lb libbsd## SYNOPSIS

In limits.h In bsd/stdlib.h Ft int Fn radixsort const unsigned char **base int nmemb const unsigned char *table unsigned endbyte Ft int Fn sradixsort const unsigned char **base int nmemb const unsigned char *table unsigned endbyte## DESCRIPTION

The Fn radixsort and Fn sradixsort functions are implementations of radix sort.These functions sort an Fa nmemb element array of pointers to byte strings, with the initial member of which is referenced by Fa base . The byte strings may contain any values. End of strings is denoted by character which has same weight as user specified value Fa endbyte . Fa endbyte has to be between 0 and 255.

Applications may specify a sort order by providing the
Fa table
argument.
If
non- **NULL**
Fa 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
Fa 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
Fa 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
Fa endbyte
has a sorting weight of 0.

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

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

These functions are variants of most-significant-byte radix sorting; in
particular, see
An D.E. Knuth Ns '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

Rv -std radixsort## ERRORS

**Bq**Er EINVAL- The value of the Fa endbyte element of Fa table is not 0 or 255.

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

## HISTORY

The Fn radixsort function first appeared in BSD 4.4