// Register Error if ID code does not match. for functions.php

registration-code.php

//----------------------------------------------
// Register Error if ID code does not match.
//----------------------------------------------

    function myplugin_check_fields($errors, $sanitized_user_login, $user_email) {

    $mystring = $user_email;
    $findme   = '.edu';
    $pos = strpos($mystring, $findme);

    if ( ! $pos === false)
        $errors->add( 'email_domain_error', __('<strong>ERROR</strong>: Please provide a non .edu email.','mydomain') );

    //if ( ! preg_match('/^(\d{5}(\d{4})?)?$/', $_POST['registrationcode']) )
    //$registerKey = $_POST['registrationcode'];
    //if ( ! $registerkey == '123' )        
    if ( ! preg_match('/^7891gza!/', $_POST['registrationcode']) )
        $errors->add( 'registerkey_error', __('<strong>ERROR</strong>: Enter a valid registration code.','mydomain') ); 
        
    return $errors;


    // if ( strpos('.edu', $_POST['user_email']) )
    //     $errors->add( 'email_domain_error', __('<strong>ERROR</strong>: Please provide a non .edu email.','mydomain') );
    
    // return $errors;


    // if ( ! preg_match('/^(\d{5}(\d{4})?)?$/', $_POST['registrationcode']) )
    //     $errors->add( 'registerkey_error', __('<strong>ERROR</strong>: Enter a valid registration code.','mydomain') );

    // return $errors;    

}