 /* Now actually open the environment */
    ret = envp-&gt;open(envp, <strong class="userinput"><code>NULL</code></strong>, env_flags, 0);
    if (ret != 0) {
        fprintf(stderr, "Error opening environment: %s\n",
            db_strerror(ret));
        goto err;
    } </pre>
      <p>
        When we call 
            <span><code class="function">open_db()</code>,</span> 
             
        which is what we use
        to open our database, we no not provide a database filename for the
        third