我是 php 新手，我正在使用 MAC OS。我最近建立了一个网站并在 localhost 下测试它。它工作正常，直到有一天我尝试重命名我的主文件夹，并在从 root 切换回我重命名的文件夹时中途退出。然后我从 root 用户注销并登录我重命名的用户。然后我发现我必须重置所有内容。应用程序文件夹已从用户主目录移到与用户文件夹相同的级别。
问题就出在这里（不知道是不是上面的动作造成的）我让一个用户用用户名和密码登录，并使用一个会话变量来存储用户名。我检查：
echo $_SESSION['name'];
echo session_status();
第一个显示我输入的用户名，第二个打印 2 所以我认为用户名存储在该会话变量中。但是，每当用户进入另一个页面时，会话变量就会被破坏。
问题是什么？
这是我为每个页面编写的作为页眉的代码。它包含登录框。它曾经工作得很好。
<?php
echo '<div id="pageheader">
<div class="wrap">
<div class="logo">
<a href="index.php"><img src="pics/1.gif" height="45px"></a>
</div>
<ul id="nav">
<li><a href="">New Arrival   /</a></li>
<li><a href="">Hot   /</a></li>
<li><a href="#">By School   /</a>
<ul >
<li><a href="">ADM</a></li>
<li><a href="">CEE</a></li>
<li><a href="">EEE</a></li>
<li><a href="">HSS</a></li>
<li><a href="">MAE</a></li>
<li><a href="">MSE</a></li>
<li><a href="">NBS</a></li>
<li><a href="">SBS</a></li>
<li><a href="">SCBE</a></li>
<li><a href="">SCI</a></li>
<li><a href="">SPMS</a></li>
<li><a href="">SCE</a></li>
</ul>
</li>
<li><a href="#">By Course   /</a>
<ul>
<li><a href="book.php?q=Mathematics">Mathematics</a></li>
<li><a href="book.php?q=Computer">Computing</a></li>
<li><a href="book.php?q=Accounting">Accounting</a></li>
<li><a href="book.php?q=Business">Business Law</a></li>
<li><a href="book.php?q=Physics">Physics</a></li>
<li><a href="book.php?q=Chemistry">Chemistry</a></li>
<li><a href="book.php?q=Biology">Biology</a></li>
</ul>
</li>
<li><a href="#">By Kind   /</a></li>
</ul>
<ul id="log">';
function generateLogin(){
echo ' <li id="login">
<a id="login-trigger" href="#">login <span>▼</span></a>
<div id="login-content">
<form action="'.$_SERVER['PHP_SELF'].'" method="post" enctype="multipart/form-data">
<fieldset class="inputs">
<input name="user" type="text" placeholder="Username" class="reqd" />
<input name="loginpw" type="password" placeholder="Password" class="reqd" />
</fieldset>
<fieldset class="actions">
<input type="submit" class="button1" value="Log in" />
<label><input name="keep" type="checkbox" value="yes" />Keep me signed in</label>
</fieldset>
</form>
</div>
</li>
<li id="signup">
<a id="signup-trigger" href="#">signup <span>▼</span></a>
<div id="signup-content">
<form action="signup.php" method="post" enctype="multipart/form-data">
<fieldset class="inputs">
<input name="username" id="username" type="text" placeholder="Username (at least 6 characters)" class="reqd user" />
<input name="email" id="email" type="email" placeholder="john@example.com" class="reqd email" />
<input id="passwd1" type="password" placeholder="Password (at least 6 characters)" class="reqd pd" />
<input name="pswd" id="passwd2" type="password" placeholder="Confirm your password" class="reqd passwd1" />
</fieldset>
<fieldset class="actions">
<input type="submit" class="button1" value="Sign up" /> <input type="reset" class="button1" />
</fieldset>
</form>
</div>
</li>
';
}
session_start();
if(!isset($_SESSION['name']) or $_GET['logout'] == 1){
if($_GET['logout'] == 1){unset($_SESSION['name']);}
if(isset($_POST['user'])){
$link = mysqli_connect('localhost','root','root','bookstore');
if (!$link){
die('Could not connect: ' . mysqli_error());
}
try {
$sql = "SELECT username FROM user
WHERE username='$_POST[user]' AND
pswd=MD5('$_POST[loginpw]')";
$sqlUser = "SELECT username FROM user
WHERE username='$_POST[user]'";
$result1 = mysqli_query($link, $sql);
$result2 = mysqli_query($link, $sqlUser);
if (!mysqli_fetch_row($result1)){
if(!mysqli_fetch_row($result2)){
throw new Exception("User ".$_POST['user']." does not exist!");
}
else{
throw new Exception("Incorrect password!");
}
}
else{
$_SESSION['name'] = $_POST['user'];
echo '
<ul id="log">
<li><a href="index.php?logout=1">Logout</a></li>
<li><a href="cart.php">Hi, '.$_POST['user'].'</a></li>
</ul>';
}
}catch(Exception $e){
echo "<script type='text/javascript'>alert('".$e->getMessage()."');</script>";
generateLogin();
}
mysqli_close($link);
}
else{
generateLogin();
}
}
else{
$name = $_SESSION['name'];
echo '
<ul id="log">
<li><a href="index.php?logout=1">Logout</a></li>
<li><a href="cart.php">Hi, '.$_SESSION['name'].'</a></li>
</ul>';
}
echo ' </ul>
<div id="search">
<form action="book.php" name="search" method="get" enctype="multipart/form-data">
<input name="q" id="q" autocomplete="off" onkeyup="showHint(this.value)" type="text" size="100" placeholder="Search..." />
<input type="submit" class="button1" value="Search" />
</form>
</div>
<div id="suggestBox">
<ul>
<div id="txtHint">
</div>
</ul>
</div>
</div>
</div>';
?>