Re: Implement C11 annex K?

[Paul Eggert <eggert at cs dot ucla dot edu>]

Russ Allbery wrote:
> how would you recommend writing this
> function without using strlcpy and strlcat?
>
> char *
> vector_join(const struct vector *vector, const char *seperator)
> {
>      char *string;
>      size_t i, size, seplen;
>
>      /* If the vector is empty, this is trivial. */
>      assert(vector != NULL);
>      if (vector->count == 0)
>          return xstrdup("");
>
>      /* Determine the total size of the resulting string. */
>      seplen = strlen(seperator);
>      for (size = 0, i = 0; i < vector->count; i++)
>          size += strlen(vector->strings[i]);
>      size += (vector->count - 1) * seplen + 1;
>
>      /* Allocate the memory and build up the string using strlcat. */
>      string = xmalloc(size);
>      strlcpy(string, vector->strings[0], size);
>      for (i = 1; i < vector->count; i++) {
>          strlcat(string, seperator, size);
>          strlcat(string, vector->strings[i], size);
>      }
>      return string;
> }

The following is certainly shorter and to my eyes considerably easier to 
follow, which appears to be the goal here (not efficiency, obviously, or 
we wouldn't be talking about strlcat).

 char *
 vector_join(const struct vector *vector, const char *sep)
 {
   char *string = xstrdup("");
   for (size_t i = 0; i < vector->count; i++) {
     char *t = xasprintf("%s%s%s", string, i ? sep : "", 
vector->strings[i]);
     free (string);
     string = t;
   }
   return string;
 }