Backslash in the end of comment lines in C/C++

Question

Does your editor/ide highlight that a++; in this C/C++ code as part of a comment?

int a=1;
//some comment \
a++;
printf("%d\n",a);

And what about this?

int a=1;
//some comment ??/
a++;
printf("%d\n",a);

Heiress

BTW, should it be a comment? I'm confused. – Kick

I think this should be community wiki. – Keening

I once asked "what's wrong" sort of question as a "c++ quiz" using this weirdness on stackoverflow (of course, replacing "\" by the trigraph "// what the heck ??/"). And the question was downvoted heavily. People didn't like how they were fooled :) – Keening

@Javier:yes -- line splicing happens in phase 2 of translation, replacement of a comment by a space happens in phase 3. – Achromaticity

The lesson, Don't have a backslash in C99 one-lined comments, please. :) – Utu

The trigraph question is tricky, personally I compile with trigraphs disabled so I am perfectly fine with my IDE not recognizing them. – Markowitz

I'm confused, can someone explain? are those a++; supposed to be part of the comment? – Chlorophyll

I’m voting to close this question because it's asking whether a particular feature is implemented in an arbitrary IDE. This is a "list-style" question that isn't useful to readers. – Outlander

Answer 1

emacs 22.3.1: No to both, sadly

Headachy

The same for my Emacs 23.1.1 Should we file a bug report? – Postprandial

<flamebait>That's why you have to switch to vim</flamebait> – Telefilm

Answer 2

vim 7.2 sees it as a comment, and gcc 3.4.3 compiles it as a comment.

Premiership

The install of vim I have (7.2, Ubuntu 10.04) sees the first one correctly, but misses on the trigraph. – Shotwell

Answer 3

VC6, Visual Studio 2003, 2005, 2008, 2010 all do.

Caviness

Answer 4

Slickedit - yes

KDevelop - yes

QT Creator - No

CodeBlocks - No

Gingersnap

Answer 5

Kate (3.4) only highlights the first test, fails hilighting the second test

// hello folks \
int a = 0;

// hello folks ??/
int a = 0;

Keening

Answer 6

Yes, TextMate does it.

Lancewood

Answer 7

Good question! I was going to ask a question about this until I found this one.

The Visual-DSP++ IDE from Analog Devices does not highlight either comment when writing in assembly or C. For example:

r1 = dm(pPointer1);      // Store pointer to r0\
r0 = lshift r1 by -16;   // Not highlighted as a comment but DOES NOT EXECUTE.
dm(i0,m1) = r0;
dm(i0,m1) = r1;

See

Answer 8

Xcode sees the first as a comment, the second not.

Jared

Answer 9

XCode and CodeWarrior handle it properly. (But not the trigraph, lol.)

Leone

Answer 10

From http://forums.topcoder.com/?module=Thread&threadID=666932

Quick note on which popular editors show this as a comment : vim - yes emacs - no :) kate - no gedit - yes netbeans - yes kwrite - yes

Postprandial