class Blob
{

private:
     static int history; // history will need to be incremented from time to time, not necessarily at construction

private:

Blob()
{}

int birthBlob()
{
Blob::history++;
}

}

class SavingsAccount
{
public:
   static void setInterest( float newValue )  // Member function
      { currentRate = newValue; }             //    that accesses
                                              //    only static
                                              //    members
private:
   char name[30];
   float total;
   static float currentRate;    // One copy of this member is
                                //    shared among all instances
                                //    of SavingsAccount
};

// Static data members must be initialized at file scope, even
//    if private.
float SavingsAccount::currentRate = 0.00154;

#include <iostream>

class T
{
   static int instances;
public:
   T()  { ++T::instances; }
   ~T() { --T::instances; }
   void show(const char *label = "") const
   {
      std::cout << label << "[member] instances = " << instances << std::endl;
   }
   friend void show(const char *label = "")
   {
      std::cout << label << "[friend] instances = " << T::instances << std::endl;
   }
};

int T::instances = 0;

int main()
{
   show("1:");
   {
      T a, b;
      show("2:");
      {
         T c;
         show("3:");
         c.show("4:");
         T d;
         show("5:");
         d.show("6:");
      }
      show("7:");
   }
   show("8:");
   return 0;
}

/* my output
1:[friend] instances = 0
2:[friend] instances = 2
3:[friend] instances = 3
4:[member] instances = 3
5:[friend] instances = 4
6:[member] instances = 4
7:[friend] instances = 2
8:[friend] instances = 0
*/

class Blob
{

static int history;  // number of blobs ever

};

int Blob::history=0;