Thread: Segmentation fault error

Yes, indeed, I meant to say, "the first non-whitespace character on the line". Oops.

BTW -- consider -W as well. It enables some other useful warnings I believe.

(Italic hashes look very strange in this font, whatever it is. They appear to have only one semi-vertical line. Well, it's actually two fused directly together, because it looks a bit thick. It's just strange. )

-W didn't do anything more with the example program, but thanks for the tip.

No, I wasn't really expecting it to. I just meant in general:

-W
Print extra warning messages for these events:

* A function can return either with or without a value. (Falling off the end of the function body is considered returning without a value.) For example, this function would evoke such a warning:

Code:

                         foo (a)
                         {
                           if (a > 0)
                             return a;
                         }

* An expression-statement or the left-hand side of a comma expression contains no side effects. To suppress the warning, cast the unused expression to void. For example, an expression such as x[i,j] will cause a warning, but x[(void)i,j] will not.
* An unsigned value is compared against zero with < or <=.
* A comparison like x<=y<=z appears; this is equivalent to (x<=y ? 1 : 0) <= z, which is a different interpretation from that of ordinary mathematical notation.
* Storage-class specifiers like static are not the first things in a declaration. According to the C Standard, this usage is obsolescent.
* The return type of a function has a type qualifier such as const. Such a type qualifier has no effect, since the value returned by a function is not an lvalue. (But don't warn about the GNU extension of volatile void return types. That extension will be warned about if -pedantic is specified.)
* If -Wall or -Wunused is also specified, warn about unused arguments.
* A comparison between signed and unsigned values could produce an incorrect result when the signed value is converted to unsigned. (But don't warn if -Wno-sign-compare is also specified.)
* An aggregate has a partly bracketed initializer. For example, the following code would evoke such a warning, because braces are missing around the initializer for x.h:

Code:

                         struct s { int f, g; };
                         struct t { struct s h; int i; };
                         struct t x = { 1, 2, 3 };

* An aggregate has an initializer which does not initialize all members. For example, the following code would cause such a warning, because x.h would be implicitly initialized to zero:

Code:

                         struct s { int f, g, h; };
                         struct s x = { 3, 4 };

From http://gcc.gnu.org/onlinedocs/gcc-3....&#37;20Options

>Italic hashes look very strange in this font, whatever it is.

Congratulations DWK, you speak Chinese!

Er -- what? How are strange italic hashes Chinese? Actually, come to think of it . . .

I do not recall there being a Chinese word that is pictorially equivalent to a #.

But yeah, I always assumed -W was some subset of -Wall. The "all" apparently is rather misleading.

But yeah, I always assumed -W was some subset of -Wall. The "all" apparently is rather misleading.

There was a message about that somewhere . . . I can't find it at the moment. Apparently, enabling all warnings is a bad idea, because some are very inefficient and give lots of false positives. The "-Wall" is what the GCC developers think is a good set of warnings to use, and you can enable and disable warnings from there.

As for the name -- it's misleading, but it's a salute to Perl's -Wall, I believe.

Originally Posted by robwhit

I don't know that I'll use -W regularly though, because as dwks said, some of them might be unwanted. But I'll give it a shot.

No, what I meant was that enabling every single one of GCC's warnings would be a bad idea. However, even "-W -Wall" doesn't even come close to enabling all of its warnings. I highly recommend using "-W -Wall", or -Wextra if you don't mind the extra typing. (Sorry, couldn't resist.)

[edit] Personally, I hate any extra typing at all. alias is fantastic. [/edit]

Don't look at me, dwk's the one who knows chinese.

I deny everything.

But it (#) looks kind of like this: http://en.wikipedia.org/wiki/Image:C...r_Niu_Trad.png

Sort of. If you squint really hard, take your glasses off (if you don't have glasses, borrow someone else's!), and walk as far backwards as the walls of the room you're currently in allow. (If you're outside . . . about 20 feet or so.)

Originally Posted by dwks

No, what I meant was <<snip>>

Oh, ok.

I deny everything.


Sort of. If you squint really hard, take your glasses off (if you don't have glasses, borrow someone else's!), and walk as far backwards as the walls of the room you're currently in allow. (If you're outside . . . about 20 feet or so.)

I'm glad you agree with me.

Personally, I'm a believer in enabling as many warnings (or, better, errors) as I can from a compiler ...

So does matsp! http://cboard.cprogramming.com/member.php?u=26843 (And I.)

I usually use "-W -Wall" for older versions of GCC, along with "-ansi -pedantic" for newer ones -- the last two can indeed cause warnings in standard header files in GCC 2.95, at least.

I've never really had cause to try out other options like --std, except for --std=c99 occasionally. Oh, and a few things like -Wno-endif-labels to deal with the recent Debian SDL 1.2.12 annoyance . . . .

I tend to disable the warning for entire files, because I don't like messing around with pragmas. Of course, I enable the warning occasionally and go through each occurrence of the warning to see if it's something I really want to ignore or not . . .

If there were several warnings involved, I suppose it would probably be better to use pragmas. What do you do?

I'd probably split it. But I want to know what others would do. Partly because I'm not sure if splitting the file would work in RL... unforeseen problems and stuff.