#include <iostream>
using namespace std;

class TestStaticVariables
{
 // Private member variable:
 static const double static_double_variable;
public:
 // Constructor:
 TestStaticVariables()
 {
  // Initialization:
  static const double static_double_variable = 20.0;
  cout << static_double_variable;
 }
 // Member Function:
 void test();
};

void TestStaticVariables::test()
{

//cout << static_double_variable;
}

int main(int argc, char* const argv[])
{

 TestStaticVariables test_instance;

 return 0;
}

#include <iostream>

class Foo {
    static const double _bar;

public:
    Foo();

    void Bar();
};

const double Foo::_bar = 20.0;

Foo::Foo() {
    std::cout << Foo::_bar << std::endl;
}

void Foo::Bar() {
    std::cout << Foo::_bar << std::endl;
}

int main( int argc, char *argv[] ) {
    Foo f;
    f.Bar();

    return 0;
}

// Initialization:
   static_double_variable = 20.0;

// Private member variable:
 static const double static_double_variable;

const double  TestStaticVariables::static_double_variable = 20.0;