How can I highlight code differences

Question

Sometimes a code snipplet included in the original question is almost working, but not quite, and only requires a small fix. But sometimes it is important to show contextually where this fix goes (rather than just say "substitute X with Y"). As an example, in one of my recent answers the "fix" is only 11 additional characters out of more than 100. I think it will increase clarity if the differences are highlighted.

Is there a easy way to high light code differences?

I ask because in a "code" block, the bold and italics mark-ups are ignored.

Answer 1

Since Jukka forgot to include the source code for his answer, here it is:

<pre>
Foo <b><i>bar</i></b> baz
Foo <s>baz</s> bah
</pre>

Answer 2

You might use comments in your code like:

% Look! Here is what I changed!

I know that it doesn't sound like an elegant solution, but so far the SE engine doesn't include a diff tool :)

Answer 3

Examples:

Foo bar baz
Foo baz bah