Programming

Thanks to you both. That step is passed. But assignment failed. I think it should work. why not?

(*st)->type = tp; //Segmentation fault.

(gdb) p *st
$1 = (site *) 0x31716573
(gdb) p *st->type
Cannot access memory at address 0x31716573
(gdb) p *st
$2 = (site *) 0x31716573
(gdb) set *st->type=tp
Cannot access memory at address 0x31716573
(gdb) set st->type=tp
Cannot access memory at address 0x31716573
(gdb) pt *st
type = struct _site {
int type;
char A;
char B;
} *

Assign it to the proper member...note the difference

Code:

*st->type = tp; /* assumes tp is an integer */

Here is the code:

site **s;
make_site(s,'-', '-', 0);

In make_site:

if( *st == NULL ) {
*st = (site *) malloc(sizeof(site));
if( *st == NULL ) {
exit(1);
}
}

(*st)->type = tp;
(*st)->A = a;

-----------------------------------------
here is the information from gdb

(gdb) p *st
$13 = (site *) 0x31716573
(gdb) p *(*st->type)
Cannot access memory at address 0x31716573
(gdb) pt *st
type = struct _site {
int type;
char A;
char B;
} *
(gdb) p *st
$14 = (site *) 0x31716573
(gdb) p *st->type
Cannot access memory at address 0x31716573

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

tp is of integer. it is right. *st->type can not be accessed, why? It is strange

These code exists in a function. Is it the environment which lead to this?

After implementing an instance of site using make_site in main function, make_site in another function can work well. If removing the instance from main function, make_site still can not work in the function.

How do we interprete it?

Can you post your code in CODE tags otherwise it is hard to understand what you are talking about.

Certainly it can be posted. Let me do so later since I am coding on its output.

Thanks