Content Below Post Code Not Working - php

Question

I am using this code to add some buttons with shortcode in functions.php## Heading ## then it is working :
function add_after_post_content($content) {
if(!is_feed() && !is_home() && is_singular() && is_main_query()) {
$content .= '<p><b>Setup/Medicine Download<b></p>[maxbutton id="1"]';
$content .= '[maxbutton id="2"]';
$content .= '[maxbutton id="3"]';
}
return $content;
}
add_filter('the_content', 'add_after_post_content');
But when I add some Html code after that then it does not work :
function add_after_post_content($content) {
if(!is_feed() && !is_home() && is_singular() && is_main_query()) {
$content .= '<table style="border: solid 1px #ffffff;width:100%;">
<tbody>
<tr>
<td>
<h3><b><span style="color: #555; ">About Author</span> </b>
<input type="hidden" name="stats" value="2498">
</h3>you can be an author too, join mhktricks and show you skills</td>
<td style="border: solid 1px #ffffff;" align="right">
<a href="http://mhktricks.net/user-registration/" target="_blank">
<input class="p2graybtn" style="height: 26px; width:150px;" type="button" value="Join Us">
</a>
</td>
</tr>
</tbody>
</table>
<hr>
<table style="border: solid 1px #ffffff;">
<tbody>
<tr>
<td>
<?php echo get_avatar( get_the_author_meta( 'user_email' ), 70 ); ?>
</td>
<td style="border: solid 1px #ffffff;">
<table style="border: solid 1px #ffffff;">
<tbody>
<tr>
<td>
<span style="color: #555;font-size:20px;font-family: Open Sans;font-weight: 400;font-style: normal;text-decoration: none;">
<?php echo get_the_author(); ?>
</span>
<br><div style="margin-left:1px;">
<?php echo get_author_role(); ?>
<span style="position:relative;top:1px;margin-left:5px;"><img src="http://i2.wp.com/codex.onhax.net/img/verified.png" height="12" width="12"></span>
</div>
</td>
<td style="border: solid 1px #ffffff;">
<div style="margin-left: 3px;margin-top: -17px;border: #B8B8B8 1px solid;border-radius:2px;padding: 0px 5px 0px 5px;font-size:10px;">
<?php the_author_posts(); ?> POSTS</div>';
</td>
</tr>
</tbody>
</table><div style="margin-top:-12px;">
</div>
<div style="margin-left:3px;margin-top:2px;padding-right:60px;">
<?php the_author_meta( 'description' ); ?>
<a class="author-link" href="<?php echo esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ); ?>" rel="author">
View all posts by me
<?php get_the_author(); ?>
<span class="meta-nav">→</span>
</a>
</div>
</td>
</tr>
</tbody>
</table>
<hr color="white">
<hr color="white">
<table style="border: solid 1px #ffffff;width:100%;">
<tbody>
<tr>
<td>
<h3><b><span style="color: #555; ">Discussion</span></b></h3>
share your knowledge.mind to help others</td>
<td style="border: solid 1px #ffffff;" align="right">
<a href="#" class="show-comments">
<input class="p2graybtn" style="height: 26px;" type="button" value="Toggle Comments">
</a>
</td>
</tr>
</tbody>
</table>';
}
return $content;
}
add_filter('the_content', 'add_after_post_content');
When I add the above code the page even doesn't load.
I just want to add author box below posts but it does not work. Help Please !

Answer 1

If you'd bothered to look, you have a ' in your html, which is terminating your string assignment:
[...long snip...] the_author_posts(); ?> POSTS</div>';
^---
</td>
which turns that </td> into PHP code, causing a fatal parse error.
This is why massive multi-line strings like this are a horrible idea. If you need to dump text like that, use a HEREDOC, or drop out of PHP mode. e.g.
$content = <<<EOL
blah blah blah all your html here blah blah blah
EOL;
HEREDOCs removes the need to worry about quotes.
You should also turn on display_errors and error_reporting, which would have told you about the fatal error. They should NEVER be off on a devel/debug system.