• Yves Jacoby (20/20) Jan 27 2006 Hi,
• Tom S (11/15) Jan 27 2006 It fails because D strings aren't ended by zeros. printf is trying to
• Yves Jacoby (2/11) Jan 27 2006 Thank you, first D try. :-)
• xs0 (8/38) Jan 27 2006 try

Yves Jacoby <yves kloune.net> writes:

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;
}

Tom S <h3r3tic remove.mat.uni.torun.pl> writes:

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 +/

Yves Jacoby <kloune gmail.com> writes:

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. :-)

xs0 <xs0 xs0.com> writes:

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