How can i pass input type value to another php file in php

Question

I want pass input type value to another php file,i'm getting a variable to input type value i need to pass the value to other file.when ever i submitted form it is showing like that issue

(Notice: Undefined variable: category in C:\xampp\htdocs\essae\quote_enquiry.php on line 9 Notice: Undefined variable: product in C:\xampp\htdocs\essae\quote_enquiry.php on line 10).

Here my HTML code:

<form action="quote_enquiry.php" method="post"> 
        <div class="mini_width_left">
        <input type="text" name="name" id="quick_name" placeholder="Name"/>      
        <input type="text" name="email" id="quick_email" onblur="quickcheckEmail(this.value);" placeholder="Email" />

        </div>
        <div class="mini_width_right">
        <input type="text" name="phone" id="quick_phone" onKeyPress="return isNumberKey(event);"  placeholder="Phone" />
        <input type="text" name="location" id="quick_location" placeholder="Location" />  
</div>
        <input type="text" name="category" id="category" value="<?php echo $category ?>" /> 
        <input type="text" name="product" id="product" value="<?php echo $product ?>" /> 
        <textarea name="requirement" placeholder="Message..." required=""></textarea>
        <input type="submit" name="get_submit" value="SUBMIT" >
</form>

Here PHP file:quote_enquiry.php

Error:

Notice: Undefined variable: category in C:\xampp\htdocs\essae\quote_enquiry.php on line 9 Notice: Undefined variable: product in C:\xampp\htdocs\essae\quote_enquiry.php on line 10

<?php

    if(isset($_POST['get_submit'])){

      $name         = $_POST['name'];
      $email        = $_POST['email'];
      $mobile       = $_POST['phone'];
      $location     = $_POST['location'];
      $category     = $_POST['category'];
      $product     = $_POST['product'];
      $decs         = $_POST['requirement'];
      echo "<pre>";print_r($_POST);die;
    }
    ?>