I've a range of publish IDs found in $postarray. I must print the posts akin to these IDs in Wordpress. The code I'm using is the following:

query_posts(array('post__in' => $postarray));
if (have_posts()) :
    while (have_posts()) : the_post();
        the_title();
        the_excerpt();
    endwhile;
endif;

Regardless of this, the loop prints the newest posts and never the posts included in the array. How do i have wordpress make use of the publish IDs I supply within the array and print individuals posts so as?

You might want to get out of the conventional Wordpress Loop with this...

Try to make use of the get_publish() function that takes the ID of the publish and returns an item that contains a the particulars from the publish within the usual OBJECT or Connect or Number Array format.

See full-explanation of get_post().

You are able to develop a custom routine to parse the items within the array. Here is a brief example:

function get_posts_by_ids( $postarray = null ) {
    if( is_array( $postarray ) )
    	foreach( $postarray as $post ) {
    		$post_details = get_post( $post[0] );

    		// Title
    		echo $post_details->post_title;
    		//Body
    		echo $post_details->post_content ;
    	}
}

Hope this can help :)