Wrapping a C library

Hi,

I'm creating a wrapper class for libdict (yes, I realise this has 
possibly been done before), and running into a segfault problem.  I 
realise this has possibly more to do with bad C than with Foundation 
per se, but I'd appreciate some help :-)

libdict has a function ld_define, declared thus in libdict.h:
struct ld_defanswer **ld_define(struct ld_conn *conn, char *word);

and I have an object GLDictionaryAccessor which contains the following 
method:
-(struct ld_defanswer **)define:(NSString *)w
{
	return ld_define(connection,[w cString]);
}

I wrote an ObjC CLI interface for the class [this is, apart from for 
testing purposes a bit pointless, as I fgets c strings, 
stringWithCString them, then use cString in the wrapper object...] 
which does this:

		if(!strcasecmp(input,"define"))
		{
			struct ld_defanswer **d;
			printf("Define word: ");
			fgets(arg1,BUFSIZ,stdin);
			arg1[strlen(arg1)-1]='\0';
			a1=[NSString stringWithCString:arg1];
			d=[da define:a1];
			if(d==NULL)
			{
				printf("No results for '%s'\n",arg1);
			}
			else
			{
				while(d[i]!=NULL)
				{
					printf("Got HERE too, d[i]=%d\n",d[i]);
					printf("Found definition:\n%s\n",d[i]->ld_ansdef);
					i++;
				}
			}
			continue;
		}

which looks, to me at least, the same as the code in a C CLI interface 
for the library, which does this:
         struct ld_defanswer **ans;
         int i = 0;

         if(!(ans = ld_define(conn, arg))) {
                 printf("No results for '%s'.\n", arg);
         } else {
                 while(ans[i]) {
                         printf("Found in dictionary '%s':\n", 
ans[i]->ld_ansdict);
                         printf("%s\n", ans[i]->ld_ansdef);
                         i++;
                 }
         }

except that mine segfaults and theirs doesn't :-(.  gdb doesn't offer 
much information:
dictstep> define
Define word: foo
Got HERE too, d[i]=1851596885

Program received signal EXC_BAD_ACCESS, Could not access memory.
0x000032bc in main (argc=1, argv=0xbffffb58) at dictstep.m:169
169                                             printf("Found 
definition %s:\n",d[i]->ld_ansdef);
(gdb) bt
#0  0x000032bc in main (argc=1, argv=0xbffffb58) at dictstep.m:169
(gdb) quit

I am lost.

Cheers,

Graham.
-- 
Graham Lee                       GPG Key ID: 01D5B9D8
UNIX Systems Manager,
Oxford Physics Practical Course
http://nextstep.sdf-eu.org               01865 273450