ch8_24.cpp

本文档是C＋＋程序设计教程系列的部分辅助代码。

//**********************
//**    ch8_24.cpp    **
//**********************

#include <iostream.h>
#include <math.h>

double sigma(double(*func)(double), double dl, double du)
{
  double dt=0.0;
  for(double d=dl; d<du; d+=0.1)
    dt += func(d);     //用函数指针调用函数
  return dt;
}

void main()
{
  double dsum;
  dsum=sigma(sin, 0.1, 1.0);    //sin函数为实参赋给函数指针func
  cout <<"the sum of sin from 0.1 to 1.0 is " <<dsum <<endl;
  dsum=sigma(cos, 0.5, 3.0);    //cos函数赋给函数指针func
  cout <<"the sum of cos from 0.5 to 3.0 is " <<dsum <<endl;
}