1#include <stdio.h>
2#include <stdlib.h>
3
4#define _GNU_SOURCE
5#include <string.h>
6
7int main(int argc, char **argv)
8{
9  char a[] = "The spazzy orange tiger jumped over the tawny jaguar.";
10  char *b, *c;
11  char *d, *e;
12
13  size_t l = strlen (a);
14  fprintf (stderr, "strlen: %zd\n", l); // strlen: 53
15
16  b = (char *) malloc((l + 3)); // Extra space for some zeros.
17  b[l] = 'X';
18  b[l + 1] = 'X';
19  b[l + 2] = 'X';
20  c = stpncpy (b, a, l + 3);
21
22  fprintf (stderr, "equal: %d\n", strcmp (a, b)); // equal: 0
23  fprintf (stderr, "retlen: %zd\n", c - b); // retlen: 53
24  fprintf (stderr, "last: '%c'\n", *(c - 1)); // last: '.'
25  fprintf (stderr, "zero0: %d\n", *c); // zero0: 0
26  fprintf (stderr, "zero1: %d\n", *(c + 1)); // zero1: 0
27  fprintf (stderr, "zero2: %d\n", *(c + 2)); // zero2: 0
28
29  d = (char *) malloc (l - 1); // No room for zero termination or dot.
30  e = stpncpy (d, b, l - 1);
31
32  fprintf (stderr, "equal: %d\n", strncmp (b, d, l - 1)); // equal: 0
33  fprintf (stderr, "retlen: %zd\n", e - d); // retlen: 52
34  fprintf (stderr, "last: '%c'\n", *(e - 1)); // last: 'r'
35
36  free (b);
37  free (d);
38  return 0;
39}
40