Date: Fri, 02 Nov 2001 10:56:11 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Fabio Miranda <fmirand@yahoo.com> Cc: freebsd-chat@FreeBSD.org Subject: RE: struct hostent Message-ID: <XFMail.011102105611.jhb@FreeBSD.org> In-Reply-To: <20011102161519.40762.qmail@web11504.mail.yahoo.com>
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On 02-Nov-01 Fabio Miranda wrote:
> Hi, i am coding a small c program in order to learn
> network programming:
> main(int argc, char *argv[]){
> struct hostent *host;
> ....
> if((host=gethostbyname(argv[1])=NULL)){
> perror("gethostbyname");
> exit(-1);}
This should be:
if ((host = gethostbyname(argv[1])) == NULL) {
Note the "==" check for NULL. You are assigning NULL to host effectively,
causing your core dump. I would also persoally recommand a slightly different
style, but that is a matter of personal opinion I suppose.
> /* now, i want to print out all the hostent struct
> information */
> printf("struct hostent{\n");
> printf("char *h_name: %s", host->h_name);
> printf("char **h_aliases:%s\n", host->h_length);
> printf("int h_addrtype: %d\n", host->h_addrtype);
> printf("int h_length: %d\n", host->h_length);
> printf("char **h_addr_list: %d\n",
> host->h_addr_list);
> }
> }
> This program core dumped, it may crash because i am
> trying to print an char array (h_addr_list, right?), I
> want to know how can i print all the information store
> in a struct hostent?, especiality the ip address.
>
> thanks
>
>
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--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
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