title: ph error : notice : undefined variable : id in c:\wamp how to fix it?? $_SESSION error
body: <p>i am creating android application that need connection with php mysql  the application work perfect in the android side.</p>
  
  <p>the problem is in the php file  when i am trying to store $_SESSION for id from file to file to file the php display an error :
   <strong>Undefined variable id in c:\wamp\www\android_connect\status.php on line 53</strong></p>
  
  <p>how can i fix this error i will post the three file of php that contain</p>
  
  <ul>
  <li>register</li>
  <li>login</li>
  <li>status</li>
  </ul>
  
  <h1>register.php</h1>
  
  <pre><code>&lt;?php
  
  /*
   * Following code will create a new product row
   * All product details are read from HTTP Post Request
   */
  
  // array for JSON response
  $response = array();
  if(empty($_POST['user']) || empty($_POST['password'])){
         $response["success"] = 0;
         $response["message"] = "enter Both Fields";
          // echoing JSON response
          die (json_encode($response));
  
  
  }
  
  // check for required fields
  else if (isset($_POST['user']) &amp;&amp; isset($_POST['password']) ) {
  
      $user = $_POST['user'];
      $password = $_POST['password'];
  
  
      // include db connect class
      require_once __DIR__ . '/db_connect.php';
  
      // connecting to db
      $db = new DB_CONNECT();
  
      //check if the user exist !!!!
      $check = mysql_query("SELECT * FROM users WHERE user = '$user'");
  
      $count_query = mysql_num_rows($check);
      if($count_query &gt; 0){
         $response["success"] = 0;
         $response["message"] = "User Already Exist!!";
          // echoing JSON response
          die (json_encode($response));
      }else if(strlen($user)&lt;6){
  
          $response["success"] = 0;
          $response["message"] = "Your user Name Must bigger than 6 Char.";
          // echoing JSON response
          die (json_encode($response));     
      }else if(strlen($password)&lt;8){
  
          $response["success"] = 0;
          $response["message"] = "Your Password Must bigger than 8 Char.";
          // echoing JSON response
          die (json_encode($response));     
      }else{
  
      // mysql inserting a new row
      $result = mysql_query("INSERT INTO users(user, password) VALUES('$user', '$password')");
  
        //**************************
        //added  and can be deleted 
        //*************************
        $id = mysql_insert_id();
  
      // check if row inserted or not
      if ($result) {
          // successfully inserted into database
  
          //**************************
          //added  and can be deleted 
          //*************************
          $_SESSION['id'] = mysql_insert_id();
  
          $response["success"] = 1;
          $response["message"] = "User successfully created.";
  
          // echoing JSON response
          die (json_encode($response));
      } else {
          // failed to insert row
          $response["success"] = 0;
          $response["message"] = "Oops! An error occurred.";
  
          // echoing JSON response
          die (json_encode($response));
      }
    }
  } else {
      // required field is missing
      $response["success"] = 0;
      $response["message"] = "Required field(s) is missing";
  
      // echoing JSON response
          die (json_encode($response));
  }
  ?&gt;
  </code></pre>
  
  <h1>login.php</h1>
  
  <pre><code>&lt;?php
  ob_start();
  @session_start();
  
  //array for JSON response
  $response = array();
  
  // check for required fields
  if(empty($_POST['user']) || empty($_POST['password'])){
         $response["success"] = 0;
         $response["message"] = "enter Both Fields";
          // echoing JSON response
          die (json_encode($response));
  
  
  }
  
  else if (isset($_POST['user']) &amp;&amp; isset($_POST['password']) ) {
  
      $user = $_POST['user'];
      $password = $_POST['password'];
  
  
      // include db connect class
      require_once '/db_connect.php';
  
      // connecting to db
      $db = new DB_CONNECT();
  
      // mysql inserting a new row
      $sql = mysql_query("Select * from users where user='$user' and password = '$password'")or die(mysql_error());
      $count_query = mysql_num_rows($sql);
  
      if($count_query &gt;0){
      //*******************************
      //added can be deleted
      //*******************************
  
  
      $user_details = mysql_fetch_array($sql);
       $response["success"] = 1;
  
       $id = $user_details['id'];
       $_SESSION['id'] = $id; 
  
  
  
      $response['id'] = $user_details['id'];
       $response["message"] = "correct Informations";
  
     // echoing JSON response
          echo json_encode($response);
      }
       else{
          $response["success"] = 0;
          $response["message"] = "Wrong User Or Pass";
  
          // echoing JSON response
          echo json_encode($response);
      }
  }
  else {
      // required field is missing
      $response["success"] = 0;
      $response["message"] = "Required field(s) is missing";
  
      // echoing JSON response
      echo json_encode($response);
  }
  ob_end_flush(); 
  ?&gt;
  </code></pre>
  
  <h1>status.php</h1>
  
  <pre><code>        &lt;?php ob_start(); 
  //array for JSON response 
  $response = array();
  
             if(!isset($_SESSION)) { session_start();
  
  
             }
  
             if(isset($_SESSION['id'])) {
  
                $id= $_SESSION['id'];
  
             } 
  
             //var_dump ($id);
  
             // include db connect class
                 require_once '/db_connect.php';
  
                 // connecting to db
                 $db = new DB_CONNECT();
  
             // check for required fields
                if(empty($_POST['status'])){
                 $response["success"] = 0;
                 $response["message"] = "Your Text Field is empty";
                  // echoing JSON response
                     die (json_encode($response));
  
  
             } else if (isset($_POST['status'])) {
  
                 $status = $_POST['status'];
                          $sql = mysql_query("INSERT INTO status (status_text, uid)VALUES('$status', '$id')")or die(mysql_error());
  
                    if ($sql) {
                     // successfully inserted into database
  
                  $response["success"] = 1;
                     $response["message"] = "Status Saved.";
  
                     // echoing JSON response
                     die (json_encode($response));
                 } else {
                     // failed to insert row
                     $response["success"] = 0;
                     $response["message"] = "Error in saving the status.";
  
                     // echoing JSON response
                     die (json_encode($response));
                 }
                  }
  
             ob_end_flush(); ?&gt;
  </code></pre>
  
  <p>i know that the error is in the insert query but i do not know why it do not assign the sesion id to the variable $id.</p>