title: Fenced Code Blocks Extension

# Fenced Code Blocks

## Summary

The Fenced Code Blocks extension adds a secondary way to define code blocks,
which overcomes a few limitations of the indented code blocks.

This extension is included in the standard Markdown library.

## Syntax

Fenced Code Blocks are defined using the syntax established in
[PHP Markdown Extra][php].

[php]: http://www.michelf.com/projects/php-markdown/extra/#fenced-code-blocks

Thus, the following text (taken from the above referenced PHP documentation):

```md
This is a paragraph introducing:

~~~~~~~~~~~~~~~~~~~~~
a one-line code block
~~~~~~~~~~~~~~~~~~~~~
```

Fenced code blocks can have a blank line as the first  and/or last line of a
code block and they can also come immediately after a list item without becoming
part of the list.

!!! warning

    Fenced Code Blocks are only supported at the document root level.
    Therefore, they cannot be nested inside lists or blockquotes.

### Language

In addition to PHP Extra's syntax, you can define the language of the code
block for use by syntax highlighters etc. The language will be assigned as a
class attribute of the ``<code>`` element in the output. Therefore, you should
define the language as you would a CSS class - ``.language``. For consistency
with other markdown syntax, the language can *optionally* be wrapped in curly
brackets:

```md
~~~~{.python}
# python code
~~~~

~~~~.html
<p>HTML Document</p>
~~~~
```

The above will output:

```html
<pre><code class="python"># python code
</code></pre>

<pre><code class="html">&lt;p&gt;HTML Document&lt;/p&gt;
</code></pre>
```

[GitHub][]'s backtick (`\``) syntax is also supported:

````md
```python
# more python code
```
````

[GitHub]: http://github.github.com/github-flavored-markdown/

### Emphasized Lines

If you would like to have your fenced code blocks highlighted with the
[CodeHilite][] extension, simply enable that extension (remember that
[Pygments][] is its dependency) and the language of your fenced code blocks
will be passed in and highlighted appropriately.

Similar to the [colon][] syntax of the CodeHilite extension, fenced code blocks
can also have emphasized certain lines of code.

The lines can be specified with PHP Extra's syntax:

```md
~~~~{.python hl_lines="1 3"}
# This line is emphasized
# This line isn't
# This line is emphasized
~~~~
```

... or with GitHub's:

````md
```python hl_lines="1 3"
# This line is emphasized
# This line isn't
# This line is emphasized
```
````

[CodeHilite]: code_hilite.md
[Pygments]: http://pygments.org/
[colon]: code_hilite.md#colons

## Usage

See [Extensions](index.md) for general extension usage. Use `fenced_code` as
the name of the extension.

This extension does not accept any special configuration options.