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asearch
typesafe binary search (bsearch)
Rusty Russell <rusty@rustcorp.com.au>
An ordered array of objects can be efficiently searched using a binary search algorithm; the time taken is around log(number of elements).
This version uses macros to be typesafe on platforms which support it.
#include <ccan/asearch/asearch.h>
#include <stdio.h>
#include <string.h>
static int cmp(const char *key, char *const *elem)
{
return strcmp(key, *elem);
}
int main(int argc, char *argv[])
{
char **p;
if (argc < 2) {
fprintf(stderr, "Usage: %s <key> <list>...\n"
"Print position of key in (sorted) list\n",
argv[0]);
exit(1);
}
p = asearch(argv[1], &argv[2], argc-2, cmp);
if (!p) {
printf("Not found!\n");
return 1;
}
printf("%u\n", (int)(p - &argv[2]));
return 0;
}
LGPL