Confusing difference in raw versus shared_ptr behavior w/ static initializers

Hi everybody,

I am struggling to understand the different behavior exhibited in the
raw versus shared_ptr behavior of the static initializers in the
following small test program. Can anybody explain this to me, or is
it perhaps a compiler bug?
I am trying to get good at RAII and cannot figure this puzzle out.

Any helpful info will be much appreciated. Code pasted below. Best
regards,

Rudi

// Compiled with g++ 4.5.2 using command:
//
// g++ main.cc -o noshared -std=c++0x
// or
// g++ main.cc -o yesshared -std=c++0x -DUSED_SHARED=1
//
// How come the first case produces two lines of output and the second
only 1?
//
// % ./noshared
// cmdstring
// hello
// %
// % ./yesshared
// hello
// %

#include <string>
#include <vector>
#include <iostream>

#include <memory>

class Anac {
  std::vector<std::string> m_strings;
  Anac(void);
public:
  static Anac& getInstance(void);
  void printStrings(void);
  void addString(std::string val);
};

class Cmd {
public:
  Cmd(void);
};

static Cmd c;

Cmd::Cmd(void)
{
  Anac::getInstance().addString("cmdstring");
}

using namespace std;

#if USED_SHARED
static std::shared_ptr<Anac> singleton;
#else
static Anac *singleton;
#endif

Anac::Anac(void) : m_strings() {
}

void Anac::addString(std::string val) {
  m_strings.push_back(val);
}

void Anac::printStrings(void) {
  for (auto i = m_strings.begin(); i != m_strings.end(); ++i) {
    cout << (*i) << '\n';
  }
}

Anac& Anac::getInstance(void) {
  if (!singleton) {
#if USED_SHARED
    singleton = std::shared_ptr<Anac>(new Anac());
#else
    singleton = new Anac();
#endif
  }
  return *singleton;
}

using namespace std;

int main(int argc, char **argv)
{
  Anac::getInstance().addString("hello");
  Anac::getInstance().printStrings();
  return 0;
}