Hi,

Could someone tell me why this program segfaults ? None of the asserts fail, the print statements were because I didn't trust the asserts.

System information: gdc (GCC) 3.4.5 (gdc 0.17, using dmd 0.140, Gentoo
0.17-r1)

------------

int main(char[][] args){

        int i;

        assert(args!=null);
        printf("Argument list %d %d\n",args.sizeof,args.length);

        for(i=0;i<args.length;i++){

                printf("B");
                assert(i<args.length);
                assert(args[i]!=null);
                printf("A");
                printf("Index: %d  length: %d value: %s\n", i,
args[i].length, args[i]);
        }

        return 0;
}

Yves Jacoby wrote:
> Hi, 
> 
> Could someone tell me why this program segfaults ? None of the asserts fail,
> the print statements were because I didn't trust the asserts. 

It fails because D strings aren't ended by zeros. printf is trying to use strlen on the string arguments and thus fails, looking for the zero. Replace printf with writef or writefln and you'll be fine



-- 
-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GCS/M d-pu s+: a-->----- C+++$>++++ UL P+ L+ E--- W++ N++ o? K? w++ !O !M V? PS- PE- Y PGP t 5 X? R tv-- b DI- D+ G e>+++ h>++ !r !y
------END GEEK CODE BLOCK------

Tomasz Stachowiak  /+ a.k.a. h3r3tic +/

On Fri, 27 Jan 2006 17:43:49 +0100, Tom S wrote:

> Yves Jacoby wrote:
>> Hi,
>> 
>> Could someone tell me why this program segfaults ? None of the asserts fail, the print statements were because I didn't trust the asserts.
> 
> It fails because D strings aren't ended by zeros. printf is trying to use strlen on the string arguments and thus fails, looking for the zero. Replace printf with writef or writefln and you'll be fine

Thank you, first D try. :-)

Yves Jacoby wrote:
> Hi, 
> 
> Could someone tell me why this program segfaults ? None of the asserts fail,
> the print statements were because I didn't trust the asserts. 
> 
> System information: gdc (GCC) 3.4.5 (gdc 0.17, using dmd 0.140, Gentoo
> 0.17-r1)
> 
> ------------
> 
> int main(char[][] args){
> 
>         int i;
> 
>         assert(args!=null);
>         printf("Argument list %d %d\n",args.sizeof,args.length);
> 
>         for(i=0;i<args.length;i++){
> 
>                 printf("B");
>                 assert(i<args.length);
>                 assert(args[i]!=null);
>                 printf("A");
>                 printf("Index: %d  length: %d value: %s\n", i,
> args[i].length, args[i]);
>         }
> 
>         return 0;
> }
> 

try

writefln("Index: %d length: %d value: %s", i, args[i].length, args[i]);

The reason would be that printf is from C and expects a char*, but gets a char[], which is length first, char* second. Dereferencing length is almost guaranteed to segfault :)

BTW, this should go to digitalmars.D.learn


xs0