comment style

[Dan Bernstein]

In article <616 at caslon.cs.arizona.edu> dave at cs.arizona.edu (Dave P. Schaumann) writes:
> In article <1050:Jan701:40:4791 at kramden.acf.nyu.edu> brnstnd at kramden.acf.nyu.edu (Dan Bernstein) writes:
> |1. [ x/*p can be evaluated as a reasonable expression ]
> This is a reasonable argument against why /* is a poor choice as a comment
> starter.  However, the time to point this out was 20 years ago, when Dennis
> Ritchie was designing C.

I'm not saying that we should rush to change anything. It's just a point
to remember for the future: // comments would help avoid a common error.
Similarly, I don't think we should rush to change strcmp() to strdiff(),
but we should remember that the latter would help avoid a common error.

> |2. // is shorter and easier to type than /* */.
> |3. // is more visually striking than /* ... */.
> These are matters of personal taste.

No. #2 is an objective fact and #3 is a widely accepted principle of
visual design: parallel lines are striking. Read Tufte's books.

> |4. It is always obvious, to both human eye and mechanical parser, where
> |a // comment ends (viz., the end of the line). It is not so trivial to
> |locate the next */.
> My editor has a 'search for text' function.  Doesn't yours?

My eyes don't have a ``search for text'' function, and it takes just a
bit longer for the computer to recognize a two-character sequence than
to recognize a one-character sequence.

> |5. Placing // at the beginning of several lines is guaranteed to comment
> |out the entire section. There is no easily applied rule for /*...*/.
> Comments are not for hiding code from the compiler.

But the fact is that people want to use comments to hide code (and
text). #if/#endif is not safe for hiding code and simply doesn't work
right for hiding text.

> However, as
> another post points out, // comments can have there own pitfalls when the line
> ends with a '\'.

No, not when they're done correctly. When you have end-of-line comments
there's no need for continuation characters. *All* characters are
ignored between // and newline inclusive.

---Dan