面向对象程序设计：辛普森法求积分

#include <iostream.h>
#include <math.h>
class Base{
public://为了简化,数字域取公有
  double result,a,b,step;//Intevalue积分值，a积分下限，b积分上限
  int n;
  virtual double fun(double x)      (1)       ;//被积函数声明为纯虚函数
  virtual void Integerate(){
  cout<<"这里是积分函数"<<endl;
  }
  Base(double ra=0,double rb=0,int nn=2000){
  a=ra;   b=rb;  n=nn;  result=0;
  }
void Print(){
  cout.precision(15);
  cout<<"积分值="<<result<<endl;
  }
};
class Simpson:public Base{
public:
  void Integerate(){
  int i;
  step=(b-a)/n;
  result=      (2)       ;
  for(i=1;i<n;i+=2) result=      (3)       ;
  for(i=2;i<n;i+=2) result=      (4)       ;
  result=      (5)       ;
  }
  Simpson(double ra,double rb,int nn):      (6)        {}
};
class sinS:public Simpson{//辛普生法
public:
  sinS(double ra,double rb,int nn):      (7)       {}
  double fun(double x){return sin(x);}
};
class expS: public sinS {
public:
  expS(double ra,double rb,int nn):      (8)       {}
  double fun(double x){return exp(x);}
}; 
void main(){
  Base *bp;
  sinS ss(0.0,3.1415926535/2.0,100);
  bp=      (9)       ;
  bp->Integerate();
  bp->Print();
  expS es(0.0,1.0,100);
  bp=      (10)       ;
  bp->Integerate();
  bp->Print(); 
}