Programming style: should you return early if a guard condition is not satisfied?

Question

One thing I\'ve sometimes wondered is which is the better style out of the two shown below (if any)? Is it better to return immediately if a guard condition hasn\'t been sat

Answer 1

Style 1 is what the Linux kernel indirectly recommends.

From http://www.kernel.org/doc/Documentation/CodingStyle, chapter 1:

Now, some people will claim that having 8-character indentations makes the code move too far to the right, and makes it hard to read on a 80-character terminal screen. The answer to that is that if you need more than 3 levels of indentation, you're screwed anyway, and should fix your program.

Style 2 adds levels of indentation, ergo, it is discouraged.

Personally, I like style 1 as well. Style 2 makes it harder to match up closing braces in functions that have several guard tests.