PHP使用会话创建登录

Question

So I have a log in php file ,where after it checks if the username and password correct, it redirects to main page. The point is I want to remember which user it is, so it will be his session only.

that's log in part:

if(mysql_num_rows($result) > 0) 
{
  session_start();
  $_SESSION['username'] = $username;
  $_SESSION['password'] = $password;
  header('Location: ../Main_page/main_page.php');
}

So now on main page I use:

<?php

$user = $_SESSION['username'];
?>

and after I while if I want for example to output user name, I wanted to use for example :

<dt>Welcome, <em><?php echo $_SESSION['username']?></em></dt>

But it doesn't work... Please help me to find error in this code

Answer 1

call session_start() at the top line of your every script and always have a check whether the variables are set for authorization/debugging purposes. Something like this

 if(isset($_SESSION['username'])){

 //welcome user 
  }
else 
{
  //sorry, you need to log in
}

Make sure you also set error_reporting(E_ALL) and ini_set("display_errors", 1); before you place session_start() a the top of your script. This advice is in response to your "Please help me to find error in this code"