1 #include <iostream>
 2 using namespace std;
 3 
 4 class Base
 5 {
 6 public :
 7     Base(){}
 8     virtual ~Base(){
 9         cout<<"Base::~Base()"<<endl;
10     }
11 };
12 
13 class Derived : public Base
14 {
15 public:
16     Derived(){}
17     virtual ~Derived(){
18         cout<<"Derived::~Derived()"<<endl;
19     }
20 
21     int member;
22 };
23 
24 int main()
25 {
26     Derived *pd = new Derived[3];
27     Base *pb = new Derived[3];
28 
29     delete[] pd;
30     delete[] pb;
31 
32     return 0;
33 }

Administrator@attention /e/Code
$ g++ -g Poly.cpp -o poly -lstdc++

Administrator@attention /e/Code
$ gdb -q poly.exe
Reading symbols from e:\Code\poly.exe...done.
(gdb) b 30
Breakpoint 1 at 0x401453: file Poly.cpp, line 30.
(gdb) r
Starting program: e:\Code\poly.exe
[New Thread 5132.0x8b0]
Derived::~Derived()
Base::~Base()
Derived::~Derived()
Base::~Base()
Derived::~Derived()
Base::~Base()

Breakpoint 1, main () at Poly.cpp:30
30          delete[] pb;
(gdb) n
Derived::~Derived()
Base::~Base()

Program received signal SIGSEGV, Segmentation fault.
0x00401477 in main () at Poly.cpp:30
30          delete[] pb;
(gdb)

(gdb) p *pd
$1 = {<Base> = {_vptr.Base = 0x452b98}, member = -17891602}
(gdb) p *pb
$2 = {_vptr.Base = 0x403180}

 1 #include <iostream>
 2 using namespace std;
 3 
 4 class Base
 5 {
 6 public :
 7     Base(){}
 8     virtual ~Base(){
 9         cout<<"Base::~Base()"<<endl;
10     }
11     virtual void Method(void){
12         cout<<"Base::Mehod"<<endl;
13     }
14 };
15 
16 class Derived : public Base
17 {
18 public:
19     Derived(){}
20     virtual ~Derived(){
21         cout<<"Derived::~Derived()"<<endl;
22     }
23     virtual void Method(void){
24         cout<<"Derived::Mehod"<<endl;
25     }
26 
27     int member;
28 };
29 
30 int main(int argc, char *argv[])
31 {
32     Derived *pd = new Derived[3];
33     Base *pb = pd;
34 
35     pb++;
36     pb->Method();
37 
38     delete[] pd;
39 
40     return 0;
41 }

Administrator@attention /e/Code
$ g++ -g poly2.cpp -o poly2 -lstdc++

Administrator@attention /e/Code
$ ./poly2.exe

Administrator@attention /e/Code
$ gdb -q poly2.exe
Reading symbols from e:\Code\poly2.exe...done.
(gdb) b 35
Breakpoint 1 at 0x4013e2: file poly2.cpp, line 35.
(gdb) r
Starting program: e:\Code\poly2.exe
[New Thread 4212.0x13cc]

Breakpoint 1, main (argc=1, argv=0x2f2bc0) at poly2.cpp:35
warning: Source file is more recent than executable.
35          pb++;
(gdb) n
36          pb->Method();
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x004013f0 in main (argc=1, argv=0x2f2bc0) at poly2.cpp:36
36          pb->Method();
(gdb)