Disable WordPress’ Automatic Formatting:

The problem.
You have probably noticed that, by default, WordPress converts normal quotes to “curly” quotes, and makes other little formatting changes when a post is displayed.

This is very cool for people who publish normal content, but anyone who uses their blog to discuss code will be annoyed because, when pasted in a text editor, code with curly quotes returns syntax errors.

The solution.
Simply paste the following code in your functions.php file:

function my_formatter($content) {
	$new_content = '';
	$pattern_full = '{(\[raw\].*?\[/raw\])}is';
	$pattern_contents = '{\[raw\](.*?)\[/raw\]}is';
	$pieces = preg_split($pattern_full, $content, -1, PREG_SPLIT_DELIM_CAPTURE);

	foreach ($pieces as $piece) {
		if (preg_match($pattern_contents, $piece, $matches)) {
			$new_content .= $matches[1];
		} else {
			$new_content .= wptexturize(wpautop($piece));
		}
	}

	return $new_content;
}

remove_filter('the_content', 'wpautop');
remove_filter('the_content', 'wptexturize');

add_filter('the_content', 'my_formatter', 99);

Once that’s done, you can use the [raw] shortcode in your posts:

[raw]This text will not be automatically formatted.[/raw]

Code explanation.
Our first step here was to create a function that uses a regular expression to find the [raw] shortcode in your posts’ content.

Then we hook our my_formatter() function to WordPress’ the_content() function, which means that my_formatter() will now be automatically called every time the_content() is called.

To remove the automatic formatting, we use the remove_filter() function, which lets you delete a hook on a specific function.