Getting an article image on WordPress

articleImageFunction.php

<?php
function rh_article_image() 
{
    // If there is an image attached to the post...
    if(has_post_thumbnail()) 
    {
        // .. get its uri and echo it
        $imgarr = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full', false );
        echo $imgarr[0];
    }
    else // otherwise, use the theme's header image
    {
        // Echo the theme's header image
        // header_image();
		
        // My theme doesn't use a header image, so I use the theme's hardcoded banner image
        echo  get_theme_root_uri() . '/' . get_current_theme() . '/images/banner.jpg';
    }
}
?>