Jason

No fancy, complicated syntax highlighting here. The goal of this plugin is to allow your bbPress users to post code snippets in their forum topics and replies without having to learn anything new. Basically, any raw HTML/PHP posted within <code><pre></code> or <code><code></code> tags will automatically be converted and displayed in the forum as you’d expect it would.
And additionally, anything posted within <code><pre></code> tags will be automatically escaped from bbPress applying wpautop. This will allow for your forum users’ code snippets to keep their whitespace as they intend.

bbPress Code Snippets

Automatically display HTML/PHP code posted in bbPress topics and replies.

dwhitevisoft

WP Markdown Syntax Sugar work in conjunction with plugins such as <a href="https://wordpress.org/extend/plugins/wp-markdown/" rel="ugc">wp-markdown</a> 
and <a href="https://wordpress.org/extend/plugins/wp-highlightjs/" rel="ugc">wp-highlight.js</a>. Markdown is fantastic markup for easily 
writing blogs, and <a href="http://softwaremaniacs.org/soft/highlight/en/" rel="nofollow ugc">highlight.js</a> is an extremely easy way to highlight 
code examples. In most cases, highlight.js automatically detects the proper language for a block of code. In certain 
cases, primarily if your code example is short, highlight.js could improperly detect the language that you are using; 
that is where this plugin comes into play. By adding one line to your code blocks, you can explicitly set the language 
that you are using, allowing highlight.js to properly format your code.
The concept is inspired by the <a href="https://github.com/spjwebster/wp-markdown-syntax-highlight" rel="nofollow ugc">wp-markdown-syntax-highlight</a> 
plugin.
The usage is extremely simple. Just add a shebang as the first line of your code example with the language you are using.
<pre><code>#!ruby
class Foo < Bar
 def hello
 puts "Hello World!"
 end
end
</code></pre>
The shebang is removed, and the code is outputted as:
<pre><code><pre><code class="language-ruby">class Foo < Bar
 def hello
 puts "Hello World!"
 end
end</code></pre>
</code></pre>
Now the code block is properly formatted for highlight.js to do its magic, and the code snippet will be properly 
highlighted.

WP-Markdown-Syntax-Sugar

WP Markdown Syntax Sugar is a simple plugin that works in conjunction with Markdown code blocks and highlight.js to properly format code.

bbPress Code Snippets vs WP-Markdown-Syntax-Sugar