Constructing a simple suffix array

suffix-array.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int pstrcmp(const void *, const void *);

int
main(void)
{
	char buf[BUFSIZ];
	if (!fgets(buf, sizeof buf, stdin))
		return 1;

	size_t len = strlen(buf);
	const char *array[len];

	for (size_t i = 0; i < len; i++)
		array[i] = &buf[i];

	qsort(array, len, sizeof *array, pstrcmp);

	for (size_t i = 0; i < len; i++)
		printf("%tu\n", array[i] - buf);

	return 0;
}

int
pstrcmp(const void *p1, const void *p2)
{
	const char *const *s1 = p1;
	const char *const *s2 = p2;

	return strcmp(*s1, *s2);
}