C++ static variables

#include <iostream>
using namespace std;
float getavg(float);        //declaration
int main()//from w  w  w  .j  ava2 s. co m
{
   float data=1, avg;
   while( data != 0 )
   {
      cout << "Enter a number: ";
      cin >> data;
      avg = getavg(data);
      cout << "New average is " << avg << endl;
   }
   return 0;
}
// finds average of old plus new data
float getavg(float newdata)
{
   static float total = 0;  //static variables are initialized
   static int count = 0;    //   only once per program
   count++;                 //increment count
   total += newdata;        //add new data to total
   return total / count;    //return the new average
}