Using the Library

if (rename(old_path, new_path) < 0)
{
    fprintf(stderr, "rename %s %s: %s\n",
        old_path, new_path, strerror(errno));
    exit(1);
}

if (rename(old_path, new_path) < 0)
{
    fprintf(stderr, "%s\n",
        explain_rename(old_path, new_path));
    exit(1);
}