Why nested comments not allowed?

bethge at wums.wustl.edu bethge at wums.wustl.edu
Sat Feb 17 08:36:34 AEST 1990


In article <1523 at wacsvax.OZ>, chris at wacsvax.OZ (chris mcdonald) writes:
> raw at math.arizona.edu (Rich Walters) writes:
>>In article <236100027 at prism> ly at prism.TMC.COM writes:
>>>	I'm just curious to know why nested comments are not allowed in many 
>>>	languages.
>>Nested comments are not supported because it is difficult to tell where the
>>nesting ends.  Have you ever written a paren checker in C? (in any language?)
>>Reason 2) Why waste the computing power??  After all, it's only a comment!!
> What a stupid response!
> I don't know why they are not supported but agree that they are damn
> useful. They are easy to parse in syntactically correct programs (ever
> heard of counting?) and, after all, the computer/compiler is supposed to
> do what we tell it, not for us to bow down and minimize its work.
> If its really too hard for you to count comments I'll sell you a little
> parser for a ridiculous amount.

I must be missing something here. What are nested comments good for? The only
use  I  can  think  of  is  "commenting  out" a section of code which already
contains comments.  But C has #if ... #endif for this purpose.  So what's the
problem?

One minor thing that has always annoyed me about C is that  it  takes  *four*
keystrokes,  two  shifted and two unshifted, to make a comment.  I know, *if*
one has a smart enough editor one can define a macro to do it.  But  it  also
doesn't leave much space for end-of-line comments in indented code.

IMO the only suitable comment delimiters are <some-reserved-single-character>
and <end-of-line>. This convention saves keystrokes and space, and avoids the
hazard of accidentally "commenting out" a section of code  with  a  defective
comment terminator.  Of course, it's a problem for C, which already uses just
about every character in the ASCII set! :-)



More information about the Comp.lang.c mailing list