I usually just paste some code, select it all, and press the 101 010 button.

So, make sure you have selected your code before pressing 101 010 button.

Actually, I just format it in my editor before sending it out, it's easier imo. Just make sure you got 4 spaces before each line of code. I select all text, press tab to indent them with 4 spaces, then I copy & paste it here.

As an addition to the other answers here, all the formatting rules apply in the comments space as well as in the Q&A forms, there's just no handy formatting feature for it.

In the case I want to put code into a comment, I either add 4 spaces (if it's a short snippet) or compose the comment in the answer box first, ensure it's formatted correctly, then cut/paste it into the comment field.

The formatting is based on Markdown Syntax and you can use many of the features listed in the syntax reference here.

if you format your code with the 101010-button and work on it afterwards, sometimes that breaks the formating again.

so personally I prefer formating-tags:
< pre> < code>

This is Code

also note: all other html-tags for formatting (order and unorderd lists, bold, links etc work just as fine)

EDIT: Warning: apparently some browsers display the tags instead of formatting the code :(( booh!

Greetz, Ky.

All I do is press that button, copy my code, highlight where is says "enter code here" and then just paste. And I have also noticed that if you don't indent between curly braces it tends to not format correctly.