g++ produces segfault with normal compilation, but none with -g

Question

I'm learning C++ right now using Bruce Eckel's "Thinking in C++" and I'm in the early chapters. I've got a C and Java background. Right now I've got the following problem: When I compile the sources below with

g++ A.cpp B.cpp bmain.cpp

, the program outputs a "1" (correctly) and then a segfault. When I compile with

g++ -g A.cpp B.cpp bmain.cpp

, the exact same program produces a 1 and NO segfault! I've got to say I find this astonishing. Could someone point out what I do wrong? My OS is "Linux 2.6.35-30-generic #54-Ubuntu x86_64", my g++ is version "g++ (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5".

EDIT: Just because this seems to be an important source of the error, thanks @Evan Teran: The A constructor in the B struct never gets called! I've put a "cout << "blah" << endl;" inside and it doesn't print anything

EDIT: I've included the "return 0" at the end of main now, but that doesn't help.

A.h:

#ifndef A_H
#define A_H

#include 

class A {
public:
        int i;
        std::string str;
        void print();
        A();
};

#endif

A.cpp:

#include "A.h"
#include 
#include 

using namespace std;

void A::print() {
        cout << str << " " << i << endl;
}

A::A() {
        str = "initstr";
    i = 0;
}

B.h:

#ifndef B_H
#define B_H

#include "A.h"

class B {
private:
        int counter;
public:
        A a;
        B();
        void increase();
        int read();
};

#endif

B.cpp:

#include "B.h"

using namespace std;

B::B() {
        counter = 0;
}

void B::increase() {
        ++counter;
}

int B::read() {
        return counter;
}

bmain.cpp:

#include 
#include "B.h"

using namespace std;

int main(int argc, char **argv) {
        B b;
        b.increase();
        cout << b.read() << endl;
        return 0;
}

EDIT: I've installed g++ from the packages. My Ubuntu is also very standard.

This is what I get when I call gdb a.out core

warning: Can't read pathname for load map: Eingabe-/Ausgabefehler.
Reading symbols from /usr/lib/libstdc++.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libstdc++.so.6
Reading symbols from /lib/libm.so.6...Reading symbols from /usr/lib/debug/lib/libm-2.12.1.so...done.
done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libgcc_s.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libgcc_s.so.1
Reading symbols from /lib/libc.so.6...Reading symbols from /usr/lib/debug/lib/libc-2.12.1.so...done.
done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug/lib/ld-2.12.1.so...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Core was generated by `./a.out'.
Program terminated with signal 11, Segmentation fault.
#0  0x00007fba1049104b in std::basic_string, std::allocator >::~basic_string() () from /usr/lib/libstdc++.so.6

EDIT 2: BTW, my hardware is not faulty as far as I know and I treat the OS quite well

EDIT 3: Valgrind reports the following:

==3428== Conditional jump or move depends on uninitialised value(s)
==3428==    at 0x4ECB022: std::basic_string, std::allocator >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428==    by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== 
==3428== Use of uninitialised value of size 8
==3428==    at 0x4ECB04B: std::basic_string, std::allocator >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428==    by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== 
==3428== Invalid read of size 4
==3428==    at 0x4ECB04B: std::basic_string, std::allocator >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428==    by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==  Address 0xfffffffffffffff8 is not stack'd, malloc'd or (recently) free'd
==3428== 
==3428== 
==3428== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==3428==  Access not within mapped region at address 0xFFFFFFFFFFFFFFF8
==3428==    at 0x4ECB04B: std::basic_string, std::allocator >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428==    by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==    by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==  If you believe this happened as a result of a stack
==3428==  overflow in your program's main thread (unlikely but
==3428==  possible), you can try to increase the size of the
==3428==  main thread stack using the --main-stacksize= flag.
==3428==  The main thread stack size used in this run was 8388608.
==3428== 
==3428== HEAP SUMMARY:
==3428==     in use at exit: 0 bytes in 0 blocks
==3428==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==3428== 
==3428== All heap blocks were freed -- no leaks are possible

g++ produces segfault with normal compilation, but none with -g

2 Answers