The code below will result in a segment fault under Linux but runs on Windows.

int main(){
    char[] str="a1";
    str[0]++;
    assert(str[0]=='b');
    return 0;
}

Thomas Kuehne wrote:

> The code below will result in a segment fault under Linux but runs on Windows.
> 
> int main(){
>     char[] str="a1";
>     str[0]++;
>     assert(str[0]=='b');
>     return 0;
> }

I don't think this is a bug - it's like the C (and C++) behavior for string literals. This came up on the main thread a few days ago. It should be mentioned in the doc if it isn't already. To get a modifyable string call dup.

-Ben

In article <cj90ft$a4o$1@digitaldaemon.com>, Ben Hinkle says... <snip>
> I don't think this is a bug - it's like the C (and C++) behavior for string literals.  This came up on the main thread a few days ago.  It should be mentioned in the doc if it isn't already.  To get a modifyable string call dup.

I'd been under the impression that initialising a char[] was supposed to create a modifyable copy of the initialisation data.

But whatever the intended behaviour is, it ought to be portable.

Stewart.

In article <cj8uoq$63b$1@digitaldaemon.com>, Thomas Kuehne says...
>
>The code below will result in a segment fault under Linux but runs on Windows.
>
>int main(){
>    char[] str="a1";
>    str[0]++;
>    assert(str[0]=='b');
>    return 0;
>}

http://www.digitalmars.com/d/dcompiler.html
"
Differences from Win32 version

* String literals are read-only. Attempting to write to them will cause a
segment violation.
* The configuration file is /etc/dmd.conf
"

I thik that's it

Ant

In article <cj90ft$a4o$1@digitaldaemon.com>, Ben Hinkle says...
>
>I don't think this is a bug - it's like the C (and C++) behavior for string literals. This came up on the main thread a few days ago. It should be mentioned in the doc if it isn't already. To get a modifyable string call dup.

Hmmm. It's a shame we can't write:

#    const char[] str="a1";

to get platform-neutral behavior, isn't it?

Jill

Ben Hinkle schrieb:
> > The code below will result in a segment fault under Linux but runs on Windows.
> >
> > int main(){
> >     char[] str="a1";
> >     str[0]++;
> >     assert(str[0]=='b');
> >     return 0;
> > }
>
> I don't think this is a bug - it's like the C (and C++) behavior for
> string literals. This came up on the main thread a few days ago.
> It should be mentioned in the doc if it isn't already.

To me it isn't a bug that the code runs/crashs.

The problem is that it behaves different on different plattforms. Consider a module written on a Windows box that runs fine there but crashs when used on Linux. Now, pin-point me the problematic code ;)

Thomas

Ant schrieb:
> >The code below will result in a segment fault under Linux but runs on Windows.
> >
> >int main(){
> >    char[] str="a1";
> >    str[0]++;
> >    assert(str[0]=='b');
> >    return 0;
> >}
>
> http://www.digitalmars.com/d/dcompiler.html
> "
> Differences from Win32 version
>
> * String literals are read-only. Attempting to write to them will cause a
> segment violation.
> * The configuration file is /etc/dmd.conf
> "
>
> I thik that's it
>
> Ant

Hrrr, I've been searching through the language definition stuff, but there it is on the _compiler_ page!

Thomas

Stewart Gordon wrote:
[snip]
>
> But whatever the intended behaviour is, it ought to be portable.
> 
> Stewart.

Hear, hear!!

Stewart Gordon wrote:
> But whatever the intended behaviour is, it ought to be portable.

Next you'll want undefined expressions to have consistent undefined behaviour.  :)

The code doesn't work on Windows either anyway.

   void main ()
   {
       char [] a = "foo";
       char [] b = "foo";

       a [0] = 'b';
       printf ("%.*s %.*s\n", a, b);
   }

This prints "boo boo".

This appears to be a bug in DMD, because constant sections are definitely available and used in Windows:

   void main ()
   {
       ubyte *foo = cast (ubyte *) &main;

       printf ("%p %d\n", *foo, foo);
       *foo = *foo;
   }

This prints the address and data properly but Access Violates in the assignment, indicating that "main" is put in a read-only section. Walter, once you come back, can you explain why const data is not being put into constant sections on Windows?

I remember discussing this but it was years ago.

On Mon, 27 Sep 2004 13:28:17 +0000 (UTC), Arcane Jill <Arcane_member@pathlink.com> wrote:
> In article <cj90ft$a4o$1@digitaldaemon.com>, Ben Hinkle says...
>>
>> I don't think this is a bug - it's like the C (and C++) behavior for string
>> literals. This came up on the main thread a few days ago. It should be
>> mentioned in the doc if it isn't already. To get a modifyable string call
>> dup.
>
> Hmmm. It's a shame we can't write:
>
> #    const char[] str="a1";
>
> to get platform-neutral behavior, isn't it?

We can write that.. however the 'const' applies to the array reference, not the data it refers to, AFAIK there is no way to apply const to the data it refers to.

Regan.

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