会话不会在标签内传递。 PHP会话

I'm facing an issue where my simple dummy form doesn't pass it's session variable. There is an error code

Notice: Undefined index: username in ...login.php on line 8

Notice: Undefined index: password in ...\login.php on line 9

Wrong username or password

session start index.php

<html>
    <head></head>
<body>
<?php session_start();?>
<form action="login.php" method="POST">
     Username:<input type="text" name="username">
     Password:<input type="password" name="password">
    <input type="submit" value="Login">
</form>
</body>

</html>

Validation of the input will be passed on to login.php

<html>
<head></head>
<body>
<?php 
    session_start();
    $user = "NULL";
    $password = "NULL";
    $user = $_REQUEST["username"];
    $password = $_REQUEST["password"];


    if($user == "ali" && $password == "123"){
    $_SESSION["$user"] = $user;
    echo "Login Successful</br>"; 
    echo '<a href="logout.php">Logout</a>';
    }
    else{
     echo "Wrong username or password</br>";
     echo '<a href="index.php">Back</a>';
    }
    ?>

    <p>Welcome <?php echo htmlspecialchars($user) ?></p>


 </body>
 </html>

logout.php

    <html>
    <head></head>
<body>
<?php session_start();?>
<form action="login.php" method="POST">
     Username:<input type="text" name="username">
     Password:<input type="password" name="password">
    <input type="submit" value="Login">
</form>
</body>

</html>

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1条回答默认最新

douhe3313 2015-10-20 15:17

关注

-You are facing Undefined index error because when you directly execute login.php or reload login.php or you open it in another tab, at that time $_REQUEST is an empty array. Actually your coding of login.php is wrong, thats why you are getting Undefined index error.

-First of all session_start() must be before <!DOCTYPE html>

-$_SESSION["$user"] is wrong, use $_SESSION['user'] instead.

-Why are you using $_REQUEST? Your form method is POST, so use $_POST. Refer $_REQUEST vs $_GET and $_POST

-Session must be destroyed when user logout.

-Here is the working code...

1. index.php

<html>
    <head></head>
<body>
<form action="login.php" method="POST">
     Username:<input type="text" name="username">
     Password:<input type="password" name="password">
    <input type="submit" value="Login">
</form>
</body>

</html>

2. login.php

<?php session_start(); ?>

<!DOCTYPE html>
<html>

<head>

</head>

<body>

<?php 

if( isset($_SESSION['user']) ){
   echo 'User is already logged in.<br />';
   echo '<a href="logout.php">Logout</a>';
}
else {
    if( isset($_POST["username"]) && isset($_POST["password"]) ) {
        if($_POST["username"] == "ali" && $_POST["password"] == "123"){
            $_SESSION["user"] = $_POST["username"];
            echo "Login Successful</br>"; 
            echo '<a href="logout.php">Logout</a>';
        }
        else {
            echo "Wrong username or password</br>";
            echo '<a href="index.php">Back</a>';    
        }    
    }
}

?>
 </body>
 </html>

3. logout.php

<?php
session_start();
?>
<!DOCTYPE html>
<html>
<body>

<?php
// remove all session variables
session_unset();

// destroy the session
session_destroy();
echo "All session variables are now removed, and the session is destroyed."
?>

</body>
</html>

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