// Check if the form is submitted if ( isset( $_POST['submit'] ) ) {  // retrieve the form data by using the element's name attributes value as key  echo '<h2>form data retrieved by using the $_REQUEST variable<h2/>'  $firstname = $_REQUEST['firstname']; $lastname = $_REQUEST['lastname'];  // display the results echo 'Your name is ' . $lastname .' ' . $firstname;  // check if the post method is used to submit the form  if ( filter_has_var( INPUT_POST, 'submit' ) ) {  echo '<h2>form data retrieved by using $_POST variable<h2/>'  $firstname = $_POST['firstname']; $lastname = $_POST['lastname'];  // display the results echo 'Your name is ' . $lastname .' ' . $firstname; }  // check if the get method is used to submit the form  if ( filter_has_var( INPUT_GET, 'submit' ) ) {  echo '<h2>form data retrieved by using $_GET variable<h2/>'  $firstname = $_GET['firstname']; $lastname = $_GET['lastname']; }  // display the results echo 'Your name is ' . $lastname .' ' . $firstname; exit; } 

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