PHP develops a simple book lending system to create a public web page

In our borrowing system, the HTML in the header is fixed

and does not change as the page jumps.

In order not to write the header code repeatedly, we need to make a head.php file

Write the header HTML code to facilitate calling in each file.

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<table width="" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC" >
  <tr>
    <td bgcolor="#FFFFFF"><img src="https://img.php.cn/upload/course/000/000/008/58215f071f35b180.jpg" width="440" height="200" /></td>
  </tr>
  <tr>
    <td bgcolor="#FFFFFF"><table width="440" height="50" border="0" align="center" cellpadding="0" cellspacing="0">
        <tr>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php" title="首页">首页</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php?proid=<?php echo urlencode('网页美工');?>" title="网页美工">网页美工</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php?proid=<?php echo urlencode('大数据');?>" title="大数据">大数据</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php?proid=<?php echo urlencode('asp编程');?>" title="asp编程">asp编程</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php?proid=<?php echo urlencode('php编程');?>" title="php编程">php编程</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="index.php?proid=<?php echo urlencode('软件开发');?>" title="软件开发">软件开发</a></td>
          <td align="center" background="https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
          <a href="landing.php"  title="用户登陆">用户登陆</a>&nbsp;&nbsp;
          </td>
        </tr>
      </table></td>
  </tr>
</table>

The user’s logout function is also added here:

<td align="center" background = "https://img.php.cn/upload/course/000/000/008/58215f29827c0755.jpg">
<a href="landing.php" title="用户登陆">用户登陆</a>&nbsp;&nbsp;
  <?php
  if ($_SESSION['id']){
    echo "<a href='landing.php?tj=out' title='退出'>退出</a>";
  }
  ?>
</td>

Make a judgment on the login function page

<?php
//初始化session
if(isset($_GET['tj']) == 'out'){
  session_destroy();
  echo "<script language=javascript>alert('退出成功！');window.location='landing.php'</script>";
}
?>