I can't put whole page's code so just I'm putting only about session variable code. So code divide in to 3 page
Error is I'm getting in displaye.php i.e Undefined index: size
select-size.php
<?php session_start();
  include 'connection.php';?>
   <label for="size">size</label>
     <select class="form-control" id="size" name="size">
        <option>Chooze size</option>
        <option value="s" ><?php echo $row['s_size']; ?></option>
         <option value="m" ><?php echo $row['m_size']; ?></option>
       <option value="l" ><?php echo $row['l_size']; ?></option>
       <option value="xl" ><?php echo $row['xl_size']; ?></option>
       <option value="xxl" ><?php echo $row['xxl_size']; ?></option>
     </select>
  <a href="save-size?id=<?php echo $row['id']; ?>"> <button class="btn btn-primary" ><i class="icon-bag"></i> Add to Cart</button> </a>
- savesize.php - <?php session_start(); $_SESSION['size'] = $_POST['size']; // $_SESSION['size'] = "some masssage "; -- if i wrote msg instead of passing selected value its shows on output page ?>
3.displaysize.php
<?php
 session_start();
 //info message
   if(isset($_SESSION['size'])){ ?>
   <h2> size: <?php echo $_SESSION['size']; ?> </h2>
 <?php
  }
?>
 
     
     
    