I have tried various syntax highlighting plugins. The one I liked the most was SyntaxHighlighter Evolved. My only issue with it was that it did not filter the comment sections.
Here is how to fix that:
1. Go to your Dashboard/Plugins
2. Find the SyntaxHighlighter Evolved plugin and click Edit.
3. In the editor scroll down until you find the section with the comment “Register hooks”
4. Insert the highlighted line as shown below
5. Click “Update file”
// Register hooks add_action( 'admin_menu', array(&$this, 'register_settings_page') ); add_action( 'admin_post_syntaxhighlighter', array(&$this, 'save_settings') ); add_action( 'admin_head', array(&$this, 'admin_head') ); add_action( 'wp_head', array(&$this, 'frontend_styling') ); add_action( 'wp_footer', array(&$this, 'maybe_output_scripts'), 15 ); add_filter( 'comment_text', array(&$this, 'parse_shortcodes'), 9 ); add_filter( 'the_content', array(&$this, 'parse_shortcodes'), 9 ); add_filter( 'widget_text', array(&$this, 'parse_shortcodes'), 9 ); add_filter( 'mce_external_plugins', array(&$this, 'add_tinymce_plugin') ); add_filter( 'tiny_mce_version', array(&$this, 'break_tinymce_cache') ); add_filter( 'the_editor_content', array(&$this, 'decode_shortcode_contents'), 1 ); add_filter( 'content_save_pre', array(&$this, 'encode_shortcode_contents'), 1 ); add_filter( 'save_post', array(&$this, 'mark_as_encoded'), 10, 2 ); add_filter( 'plugin_action_links', array(&$this, 'plugin_action_links'), 10, 2 );

