Add wordpress page to another page or homepage with php

<?php

if(!function_exists("getPageContent"))
    {
        function getPageContent($pageId,$max_char)
        {
            if(!is_numeric($pageId))
            {
                return;
            }
            global $wpdb;
            $nsquery = "SELECT DISTINCT * FROM " . $wpdb->posts .
            " WHERE " . $wpdb->posts . ".ID=" . $pageId;
            $post_data = $wpdb->get_results($nsquery);
            if(!empty($post_data))
            {
                foreach($post_data as $post)
                {
                    $text_out= nl2br($post->post_content);
                    $text_out= str_replace("]]>", "]]>", $text_out);
                    $text_out = strip_tags($text_out);
                    return substr($text_out,0,$max_char);

                }
            }
        }
}

?>

and on the page where we want to include the other we have two options, first one:

<?php

   echo getPageContent(18,1500);

?>

Where the first number is the ID of the page or post in question and the second number is the number of words displayed.

Or we can do it the second way:

<?php

    $my_postid = 12;
    $content_post = get_post($my_postid);
    $content = $content_post->post_content;
    $content = apply_filters("the_content", $content);
    $content = str_replace("]]>", "]]>", $content);
    echo $content;

?>