timer tm;

 date dtStartDate = from_undelimited_string("20080116");

 date dtEndDate = from_undelimited_string("20130120");  

 date tem ;

 int count = 0;

 int gap = 0;

 if (dtStartDate > dtEndDate)

 {

  return ;

 }

 if (dtStartDate.day_of_week() == 0)

 {

  tem = dtStartDate;

 }

 else

 {

  gap = dtStartDate.day_of_week();

  tem = dtStartDate - days(gap);

 }

 for (; tem <= dtEndDate ; tem += days(7) )

 {

  ++count;

  //cout << to_iso_string( tem) << " 星期" << tem.day_of_week() << endl;

 }

 cout << "总共" << count << "个星期" << endl;

 double duration = tm.elapsed();

 cout << "总共耗时:" << duration << endl;