ads-inside-content-1.php

<?php
//adding adsense ad unit inside the article

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

add_filter( 'the_content', 'prefix_insert_post_ads' );

function prefix_insert_post_ads( $content ) {

	$ad_code1 = '<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
<!-- inContent -->
<ins class="adsbygoogle"
     style="display:block"
     data-ad-client="ca-pub-xxxxxxxxxxxxxxxxxx"
     data-ad-slot="xxxxxxxxxxx"
     data-ad-format="auto"
     data-full-width-responsive="true"></ins>
<script>
     (adsbygoogle = window.adsbygoogle || []).push({});
</script><p></p>';
	
    if ( is_single() ) {
        return prefix_insert_after_paragraph( $ad_code1, 3, $content );
    }

    return $content;
}

// Parent Function that makes the magic happen

function prefix_insert_after_paragraph( $insertion1, $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] .= $insertion1;
        }
    }

    return implode( '', $paragraphs );


}