PHP存储会话数据，在会话中存储用户标识

Question

Sorry but I'm new to this. The following code only displays 'Please login'. Code does work but it's not doing what I want it to, I'm trying to store userid in a session. Here is my code

<?php

    if(!isset($_SESSION)) session_start();


    if(isset($_POST['userid'])){
         $userid = $_POST['userid']; 
         $_SESSION['userid']=$userid;
         echo "Welcome $_SESSION[userid]";
    }

    if (!isset($_SESSION['userid'])){
        echo "Please login";
        exit;
    }
    ?>

Answer 1

session_start(); shouldn't be in your if condition, it has to be at the beginning of the script and always launched

<?php

    session_start();


    if(isset($_POST['userid'])){
        $_SESSION['userid']= $_POST['userid'];
        echo "Welcome ".$_SESSION['userid'];
    }

    if (!$_SESSION['userid']){
        echo "Please login";
        exit;
    }

Answer 2

session_start() should be at the beginning without any condition. And also one extra closing bracket ) in the second if condition statement. Try this:

 <?php
   session_start();


        if(isset($_POST['userid'])){
            $_SESSION['userid']= $_POST['userid'];
            echo "Welcome {$_SESSION['userid']}";
        }

        if (!$_SESSION['userid']){
            echo "Please login";
            exit;
        }

Answer 3

• session_start() need to be before you start to work with session.
• I suggest you to replace isset() by empty(), because empty() checked for:
  • "" (an empty string)
  • 0 (0 as an integer)
  • 0.0 (0 as a float)
  • "0" (0 as a string)
  • NULL
  • FALSE
  • array() (an empty array)
  • $var; (a variable declared, but without a value)

Answer 4

Thanks for answering. It works now, I was also defining the wrong session.