Sort

The sort API sorts n objects of sz bytes each in memory starting at base, using a caller-supplied comparator like strcmp. The library entry point you should use in most cases is sort, which is the default implementation described in the header as introsort-based.

Header

#include <sort.h>

Optional macro

COL_ALL_SORTS

If you define the macro COL_ALL_SORTS before including sort.h, the header also declares sortins, sortqs, and sortheap. The header describes these as internal raw sorts without the same tuning as the default, so they are not recommended for general use, prefer sort unless you have a specific reason to call a particular variant.

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Functions

sort

int sort(void *base, size_t n, size_t sz, int (*cmp)(void *, void *));

Sorts the n elements in place. Each element occupies sz bytes, cmp receives pointers to two elements and should return less than zero, zero, or greater than zero depending on their order, in the usual style of strcmp.

Parameters

• base — address of the first element
• n — number of elements
• sz — size of each element in bytes
• cmp — comparator

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sortins

Only declared when COL_ALL_SORTS is defined before including sort.h.

int sortins(void *base, size_t n, size_t sz, int (*cmp)(void *, void *));

Insertion sort. Same parameters as sort. Prefer sort for ordinary use.

Parameters

• base — address of the first element
• n — number of elements
• sz — size of each element in bytes
• cmp — comparator

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sortqs

Only declared when COL_ALL_SORTS is defined before including sort.h.

int sortqs(void *base, size_t n, size_t sz, int (*cmp)(void *, void *));

Quicksort. Same parameters as sort. Prefer sort for ordinary use.

Parameters

• base — address of the first element
• n — number of elements
• sz — size of each element in bytes
• cmp — comparator

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sortheap

Only declared when COL_ALL_SORTS is defined before including sort.h.

int sortheap(void *base, size_t n, size_t sz, int (*cmp)(void *, void *));

Heap sort. Same parameters as sort. Prefer sort for ordinary use.

Parameters

• base — address of the first element
• n — number of elements
• sz — size of each element in bytes
• cmp — comparator

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Example

#include <sort.h>

static int cmp_int(void *a, void *b)
{
  int x = *(int *)a;
  int y = *(int *)b;
  if (x < y)
    return -1;
  if (x > y)
    return 1;
  return 0;
}

void sort_three_ints(int *buf)
{
  sort(buf, 3, sizeof *buf, cmp_int);
}