(gdb) p root
$1 = (vertex *) 0x0
(gdb) p *root
Cannot access memory at address 0x0
What's wrong?
You can do that only if you return a pointer to vertex from make_vertex...
For this you need to change the definition of make_vertex to return a pointer to vertex instead of void.
Add return statement and change return type and it can work.
But it still fails after generating many vertices. Notice where failure occurs
This seems to be a general problem.
Thanks for all your help
____________________________________
Program received signal SIGSEGV, Segmentation fault.
0x0027ff92 in _int_malloc () from /lib/tls/libc.so.6
(gdb) bt
#0 0x0027ff92 in _int_malloc () from /lib/tls/libc.so.6
#1 0x0027f0fd in malloc () from /lib/tls/libc.so.6
#2 0x0804956e in make_vertex (ver=0xbfffb624, index=-1, se=0, ps=2)
---------- Post updated at 12:37 PM ---------- Previous update was at 11:01 AM ----------
Tried to use make_vertex. It can change memory in this way. A new trouble takes place. Allocation really gives unexpected problems.
dataset[4] changes
__________________________________________________________________
110 r = make_vertex(&rho, -1, 0, i);
(gdb) p *(dataset+3)
$33 = 0x8145200 "AATTGTAAC"
(gdb) p *(dataset+4)
$34 = 0x8145a30 "GCTGAATGA"
(gdb) n
111 first = rho;
(gdb) p *(dataset+3)
$35 = 0x8145200 "AATTGTAAC"
(gdb) p *(dataset+4)
$36 = 0xb25a90 "\210Zē"
Add return statement and change return type and it can work.
But it still fails after generating many vertices. Notice where failure occurs
This seems to be a general problem.
Thanks for all your help
____________________________________
Program received signal SIGSEGV, Segmentation fault.
0x0027ff92 in _int_malloc () from /lib/tls/libc.so.6
(gdb) bt
#0 0x0027ff92 in _int_malloc () from /lib/tls/libc.so.6
#1 0x0027f0fd in malloc () from /lib/tls/libc.so.6
#2 0x0804956e in make_vertex (ver=0xbfffb624, index=-1, se=0, ps=2)
---------- Post updated at 12:37 PM ---------- Previous update was at 11:01 AM ----------
Tried to use make_vertex. It can change memory in this way. A new trouble takes place. Allocation really gives unexpected problems.
dataset[4] changes
__________________________________________________________________
110 r = make_vertex(&rho, -1, 0, i);
(gdb) p *(dataset+3)
$33 = 0x8145200 "AATTGTAAC"
(gdb) p *(dataset+4)
$34 = 0x8145a30 "GCTGAATGA"
(gdb) n
111 first = rho;
(gdb) p *(dataset+3)
$35 = 0x8145200 "AATTGTAAC"
(gdb) p *(dataset+4)
$36 = 0xb25a90 "\210Zē"
First, if you're going to overwrite the original contents of the pointer you pass it, why bother passing in its address in the first place?
If THAT blows up, your heap is getting corrupted before you even make the call to make_vertex().
I change make_vertex as you showed. It appears to work well. But dataset is destructed. This also gives troubles since it is what the code works on
dataset[4] has a different address after a call to make_vertex
_______________________________________________________________
(gdb) p dataset[4]
$1 = 0x8b91a30 "GCTGAATGA"
(gdb) n
(gdb) p dataset[4]
$2 = 0x792a90 "\210*y"
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