$_SESSION value not being erased even after logout.

[Robinson]

I had set this value into the super global $_SESSION in the first file, file_1.php:

<?php

//there is some code here

$_SESSION['salesorder'] = 'are---io';

//remaining code, includes a form.

?>

When the submit button is clicked, the form is submitted to file_2.php 

<?php
//some code over here
if (isset($_POST['sales']) && $_POST['sales'] != ""){
    $sales = sanitize_input(trim($_POST['sales']));	
    $_SESSION['salesorder'] = $sales;
	$host  = $_SERVER['HTTP_HOST'];
	$uri   = rtrim(dirname($_SERVER['PHP_SELF']), '/\\');
	$extra = 'processSO_helper_sd.php';
	header("Location: http://$host$uri/$extra?so=".$sales);
	exit();
 }
//Begin display
 include 'inc_fn_header_and_menu.php';
//some code over here
?>

which will redirect to processSO_helper_sd.php

<?php

// Initialize session
session_start();

    $SD_ID = $_SESSION['salesorder'];
    $result = $db->query($sql);
	$row = $result->fetch_assoc();
	$rowcount =$row['row_count'];*/
	//print_r($_SESSION);//*
	$result = $tmonedb->query("SELECT COUNT(*) FROM document WHERE SD_ID = $SD_ID")->fetch_array();
	$rowcount = $result[0];
//remaining code

?>

My problem is that I cannot access the 

$_SESSION['salesorder'] in the last file processSO_helper_sd.php although I have set it twice previously. 

I could not add session_start(); in the file_2.php  because that was already added in  'inc_fn_header_and_menu.php'; 

Can someone help me with this? Thank you. Please tell me if you need any additional information.

[gw1500se]

File_1.php has no session_start. File_2.php does not have session_start at the beginning. You need to take it out of 'inc_fn_header_and_menu.php' and put it at the beginning of file_2.php.

[Robinson]

Okay,But the issue is that the inc_fn_header_and_menu.php file is a shared file, it has been already included in all other files. To remove session_start(). I will have to include session_start() in all those files.

[gw1500se]

Then you need to move the include to the beginning of the file.