Reversing a string the bad way

reverse1.c

void reverse(char str[])
{
   // Add 1 for the terminating character
   int len = strlen(str) + 1;
   char temp[len];

   // Data resides from indices 0-2
   int i = len - 2;
   for (; i >= 0; --i)
   {
      // Copy front to back
      temp[i] = str[len - (i + 2)];
   }

   // Add terminating character
   temp[len - 1] = '\0';

   // Copy into original
   strncpy(str, temp, len);

   printf("reverse: %s\n", str);
}