Session 未生成php会话代码的输出

我在PHP会话方面遇到问题。此代码将显示感谢您的注册以及相应的用户名和电子邮件id，但不会显示任何内容！请帮帮我

<?php
//initialize session data
session_start();
if(isset($_SERVER['username'])){
    echo "you are already logged in as: ".$_SERVER['username'];
}
elseif($_SERVER['REQUEST_METHOD' == 'POST']){
    if(!empty(trim($_POST['username'])) && !empty(trim($_POST['email']))){
        $uname = $_POST['username'];
        $email = $_POST['email'];
        echo "thanks for registering <br/>";
        echo "your username: $uname <br/>";
        echo "your email: $email <br/>";
    }
    else{
        echo "please fill both the fields properly";
    }
}
else{ ?>
<form action="index.html?username=overwritten" method="POST">
    <input type="text" placeholder="username here.." name="username"><br/>
    <input type="email" placeholder="email here.." name="email"><br/>
    <input type="submit" value="register">
</form>
<?php } 
?>

它还显示： 注意：第7行的/Applications/XAMPP/xamppfiles/htdocs/samiary.com/index.php中未定义的偏移量为0 在顶端

---

请帮助我，我只是一个初学者。

您在

$\u服务器['REQUEST\u METHOD']附近有错误。

。试试这个：

<?php
//initialize session data
session_start();
if(isset($_SERVER['username'])){
    echo "you are already logged in as: ".$_SERVER['username'];
}
elseif($_SERVER['REQUEST_METHOD'] == 'POST'){
    if(!empty(trim($_POST['username'])) && !empty(trim($_POST['email']))){
        $uname = $_POST['username'];
        $email = $_POST['email'];
        echo "thanks for registering <br/>";
        echo "your username: $uname <br/>";
        echo "your email: $email <br/>";
    }
    else{
        echo "please fill both the fields properly";
    }
}
else{ ?>
<form action="" method="POST">
    <input type="text" placeholder="username here.." name="username"><br/>
    <input type="email" placeholder="email here.." name="email"><br/>
    <input type="submit" value="register">
</form>
<?php } 
?>

您在

$\u服务器['REQUEST\u METHOD']附近有错误。

。试试这个：

<?php
//initialize session data
session_start();
if(isset($_SERVER['username'])){
    echo "you are already logged in as: ".$_SERVER['username'];
}
elseif($_SERVER['REQUEST_METHOD'] == 'POST'){
    if(!empty(trim($_POST['username'])) && !empty(trim($_POST['email']))){
        $uname = $_POST['username'];
        $email = $_POST['email'];
        echo "thanks for registering <br/>";
        echo "your username: $uname <br/>";
        echo "your email: $email <br/>";
    }
    else{
        echo "please fill both the fields properly";
    }
}
else{ ?>
<form action="" method="POST">
    <input type="text" placeholder="username here.." name="username"><br/>
    <input type="email" placeholder="email here.." name="email"><br/>
    <input type="submit" value="register">
</form>
<?php } 
?>

我想你需要

$\u服务器['username']

而不是

$\u会话['username']

我想你需要

$\u服务器['username']

而不是

$\u会话['username']

你需要

$\u会话['username']