From BlenderWiki

Code examples (python, c/c++, etc) should be marked-up as below.

[edit] Single line of code

[edit] <code> tag

<code>from math import *</code>

returns:
from math import *

[edit] Multiple lines of code

[edit] <pre> tag

<pre>
line 1
line 2
...
</pre>

returns

line 1
line 2
...

[edit] Starting a line with a space

By putting one or more spaces in front of each line, lines are shown as below:

line 1
line 2
...