Steven

WP-Syntax provides clean syntax highlighting using 
<a href="http://qbnz.com/highlighter/" rel="nofollow ugc">GeSHi</a> — supporting a wide range of popular 
languages. It supports highlighting with or without line numbers and maintains formatting while copying snippets of code 
from the browser.
It avoids conflicts with other 3rd party plugins by running an early 
pre-filter and a late post-filter that substitutes and pulls the code snippets 
out first and then pushes them back in with highlighting at the end. The 
result is source code formatted and highlighted the way you intended.
Usage, Supported Languages, Styling Guidelines, and Release Notes are available 
in the <a href="https://wordpress.org/extend/plugins/wp-syntax/other_notes/" rel="ugc">Other Notes</a> section.
Want to contribute? WP-Syntax can be found on GitHub. <a href="https://github.com/shazahm1/WP-Syntax" rel="nofollow ugc">Fork and submit your pull requests today!</a>
<h4>Basic Usage</h4>
Wrap code blocks with <code><pre lang="LANGUAGE" line="1"></code> and <code></pre></code> where “LANGUAGE” 
is a <a href="http://qbnz.com/highlighter/" rel="nofollow ugc">GeSHi</a> supported language syntax. 
The <code>line</code> attribute is optional. <a href="https://wordpress.org/extend/plugins/wp-syntax/other_notes/" rel="ugc">More usage examples</a>
<h3>Usage</h3>
Wrap code blocks with <code><pre lang="LANGUAGE" line="1"></code> and <code></pre></code> where “LANGUAGE” is a <a href="http://qbnz.com/highlighter/" rel="nofollow ugc">GeSHi</a> supported 
language syntax. See below for a full list of supported languages. 
The <code>line</code> attribute is optional.
Example 1: PHP, no line numbers
<pre><code><pre lang="php">
<div id="foo">
<?php
 function foo() {
 echo "Hello World!\\n";
 }
?>
</div>
</pre>
</code></pre>
Example 2: Java, with line numbers
<pre><code><pre lang="java" line="1">
public class Hello {
 public static void main(String[] args) {
 System.out.println("Hello World!");
 }
}
</pre>
</code></pre>
Example 3: Ruby, with line numbers starting at 18
<pre><code><pre lang="ruby" line="18">
class Example
 def example(arg1)
 return "Hello: " + arg1.to_s
 end
end
</pre>
</code></pre>
Example 4: If your code already has html entities escaped, use <code>escaped="true"</code> as an option
<pre><code><pre lang="xml" escaped="true">
&lt;xml&gt;Hello&lt;/xml&gt;
</pre>
</code></pre>
Example 5: PHP, with line numbers and highlighting a specific line
<pre><code><pre lang="php" line="1" highlight="3">
<div id="foo">
<?php
 function foo() {
 echo "Hello World!\\n";
 }
?>
</div>
</pre>
</code></pre>
Example 6: PHP, with a caption (file and/or file path of the source file)
<pre><code><pre lang="php" src"https://github.com/shazahm1/Connections/blob/master/connections.php">
<div id="foo">
<?php
 function foo() {
 echo "Hello World!\\n";
 }
?>
</div>
</pre><h3>Supported Languages</h3>
</code></pre>
The following languages are most supported in the <code>lang</code> attribute:
abap, actionscript, actionscript3, ada, apache, applescript, apt_sources, asm, 
asp, autoit, avisynth, bash, bf, bibtex, blitzbasic, bnf, boo, c, 
c_mac, caddcl, cadlisp, cil, cfdg, cfm, cmake, cobol, cpp-qt, cpp, 
csharp, css, d, dcs, delphi, diff, div, dos, dot, eiffel, email, erlang, 
fo, fortran, freebasic, genero, gettext, glsl, gml, bnuplot, groovy, haskell, 
hq9plus, html4strict, idl, ini, inno, intercal, io, java, java5, 
javascript, kixtart, klonec, klonecpp, latex, lisp, locobasic, lolcode 
lotusformulas, lotusscript, lscript, lsl2, lua, m68k, make, matlab, mirc, 
modula3, mpasm, mxml, mysql, nsis, oberon2, objc, ocaml-brief, ocaml, 
oobas, oracle11, oracle8, pascal, per, pic16, pixelbender, perl, 
php-brief, php, plsql, povray, powershell, progress, prolog, properties, 
providex, python, qbasic, rails, rebol, reg, robots, ruby, sas, 
scala, scheme, scilab, sdlbasic, smalltalk, smarty, sql, tcl, teraterm, 
text, thinbasic, tsql, typoscript, vb, vbnet, verilog, vhdl, vim, 
visualfoxpro, visualprolog, whitespace, whois, winbatch, xml, xorg_conf, 
xpp, z80
See the <a href="http://qbnz.com/highlighter/geshi-doc.html" rel="nofollow ugc">GeSHi Documentation</a> 
for a full list of supported languages.
(Bold languages just highlight the more popular ones.)
<h3>Styling Guidelines</h3>
WP-Syntax colors code using the default GeSHi colors. It also uses inline 
styling to make sure that code highlights still work in RSS feeds. It uses a 
default <code>wp-syntax.css</code> stylesheet for basic layout. To customize your styling, 
copy the default <code>wp-content/plugins/wp-syntax/wp-syntax.css</code> to your theme’s 
template directory and modify it. If a file named <code>wp-syntax.css</code> exists in 
your theme’s template directory, this stylesheet is used instead of the default. 
This allows theme authors to add their own customizations as they see fit.
<h3>Advanced Customization</h3>
WP-Syntax supports a <code>wp_syntax_init_geshi</code> action hook to customize GeSHi 
initialization settings. Blog owners can handle the hook in a hand-made plugin 
or somewhere else like this:
<pre><code><?php
add_action('wp_syntax_init_geshi', 'my_custom_geshi_styles');

function my_custom_geshi_styles(&$geshi)
{
 $geshi->set_brackets_style('color: #000;');
 $geshi->set_keyword_group_style(1, 'color: #22f;');
}
?>
</code></pre>
This allows for a great possibility of different customizations. Be sure to 
review the <a href="http://qbnz.com/highlighter/geshi-doc.html" rel="nofollow ugc">GeSHi Documentation</a>.

WP-Syntax

WP-Syntax provides clean syntax highlighting for embedding source code within pages or posts.

apfelbox

Integrates the <a href="https://github.com/LeaVerou/prism" rel="nofollow ugc">Prism Syntax Highlighting Library</a> in WordPress.
It is called detached, since the code examples are not stuffed into the rich text editor, together with all the 
other texts and content, but they are added separately as custom fields and just referenced via short tags (like footnotes).
Check Other Notes for usage documentation.
The official development repository is <a href="https://github.com/apfelbox/Prism-Detached" rel="nofollow ugc">hosted on Github</a>.
<h3>Usage</h3>
The basic procedure is:
<ol>
<li>Create a custom field and paste the code into it.</li>
<li>Insert the <code>[prism ...]</code> shorttag in your code, where you want the code block to appear.</li>
</ol>
<h4>Shorttag</h4>
<pre><code>[prism key=".." language=".." line=".." line_offset=".." post=".."]
</code></pre>
<ul>
<li><code>key</code>: the name of the custom field, which contains the code (required)</li>
<li><code>language</code>: the language to highlight</li>
<li><code>line</code>: highlighted lines (for syntax, check the <a href="http://prismjs.com/plugins/line-highlight/" rel="nofollow ugc">offical docs</a>)</li>
<li><code>line_offset</code>: the offset, with which the line numbering should start</li>
<li><code>post</code>: if you want to include a code piece of another post, you can explicitly specify the post id here</li>
</ul>
<h4>Cached Assets loader</h4>
The plugin includes (from v1.3 on) a cached assets loader, so that all needed assets are concatenated into 
one js and one css file to minimize the HTTP requests. 
To make use of the cached assets loader, just create a directory <code>/cache/</code> inside your plugin directory and make it writable for PHP.
<h4>Supported languages</h4>
Only the ones from the official PrismJS repository
<ul>
<li>bash (Bash Unix Shell)</li>
<li>c</li>
<li>clike</li>
<li>coffeescript</li>
<li>cpp (C++)</li>
<li>css</li>
<li>groovy</li>
<li>java</li>
<li>javascript</li>
<li>markup (like: xHTML, MathML, SVG, LaTeX, RSS, XML, OWL, etc.)</li>
<li>php</li>
<li>python</li>
<li>scss (Sassy CSS)</li>
<li>sql</li>
</ul>
<h4>Creating Custom Extensions</h4>
Please read the wiki page: <a href="https://github.com/apfelbox/Prism-Detached/wiki/Creating-A-Custom-Extension" rel="nofollow ugc">Creating A Custom Extension</a>.

Prism Syntax Highlighter (detached)

Adds Prism Syntax Highlighting to WordPress, using custom fields for your code examples.

WP-Syntax vs Prism Syntax Highlighter (detached)