Get page content by page name or id in Wordpress

// By Page name

<?php
$page = get_page_by_title( 'controls' );
$content = apply_filters('the_content', $page->post_content);
echo $content;
?>

//By page id

<?php
$id=31;
$post = get_post($id);
$content = apply_filters('the_content', $post->post_content);
echo $content;
?>