在文章段落插入ads代码

//Insert ads after second paragraph of single post content.

add_filter( 'the_content', 'prefix_insert_post_ads' );

function prefix_insert_post_ads( $content ) {
   
    $ad_code = '<p>here...</p>';

    if ( is_single() && ! is_admin() ) {
        return prefix_insert_after_paragraph( $ad_code, 4, $content );
    }
   
    return $content;
}
 
// Parent Function that makes the magic happen
 
function prefix_insert_after_paragraph( $insertion, $paragraph_id, $content ) {
    $closing_p = '</p>';
    $paragraphs = explode( $closing_p, $content );
    foreach ($paragraphs as $index => $paragraph) {

        if ( trim( $paragraph ) ) {
            $paragraphs[$index] .= $closing_p;
        }

        if ( $paragraph_id == $index + 1 ) {
            $paragraphs[$index] .= $insertion;
        }
    }
   
    return implode( '', $paragraphs );
}