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From: bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: Which code style do you prefer the most?
Date: Thu, 27 Feb 2025 14:18:40 +0000
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On 27/02/2025 12:56, Ar Rakin wrote:
> bart <bc@freeuk.com> writes:
> 
>> // isn't devoid of quirks (this is still C after all), for example:
>>
>>     fopen(file,"rb");   // open file in \windows\system32\
>>     fread(...);
>>
>> Here, the // line continues onto the next, so that the fread is
>> commented out. But they are fewer.
> 
> Interesting. Isn't this considered a compiler bug?

It's to do with how C is defined, which requires that its implementation 
corresponds to series of phases.

Then line-splicing, which combines two lines if the first ends with \, 
is done before processing // comments.

  I am aware that you
> can do the same thing with strings like this:
> 
> fprintf(stderr, "multi\
> line\
> strings\
> are fun.");
> 
> I can understand how this might be useful; but with *comments*?? Was
> that actually a thing in the official C standards?

It's isn't that useful for strings; the following is simpler and also works:

   "multi"
   "line"
   "string"

But it is needed for multi-line macros, as C's proprocessor is strictly 
line-oriented and a macro definition must fit onto one line.

So lines spliced with \ can be used to combine multiple lines into one. 
A side-effect is that you can't use // comments for individual lines of 
a multi-line macro, it would screw things up.

> To me it just feels like a compiler bug that was never fixed.

To me the whole of C feels like one huge language bug!

The way line splicing works has even weirder repercussions; any token 
can be split across lines:

i\
n\
t abc;      // split 'int' across 3 lines

/\
/ This is a '//' comment with // split across two lines

/\
* This is a /* ... comment */

"ABC\\
nDEF"      // A split string escape code

if (a =\
= b) ...

In fact, any C source file can be written with one character per line, 
plus the \ line continuation.