2010年广州周立功单片机(致远电子) 机试题(3)答案

答案不标准也不一定是最佳，仅供参考

#include <stdio.h>
#include <stdlib.h>

double TestFounc(double x)
{
 return (x+1);
}

double TestFounc2(double x)
{
 return x;
}

double DJF(double xStart,double xEnd,double (*Founc)(double x))//利用梯形近似求出函数曲线与X轴围成的面积
{
 double y1,y2,RetValue=0,cur,dx;
 dx=(xEnd-xStart)/65536;
 y2=Founc(xStart);

 for(cur=xStart+dx ; cur <= xEnd ; cur+=dx)
 {
  y1=y2;
  y2=Founc(cur);
  RetValue+=(y1+y2)*dx/2.0;
 }
 return RetValue;
}

void main()
{
 double RetValue = DJF(2,4,TestFounc);
 printf("测试函数y=x+1，XStart=2,XEnd=4积分结果：%lf/n",RetValue);

 RetValue = DJF(-1,1,TestFounc2);
 printf("测试函数y=x，XStart=-1,XEnd=1 积分结果：%lf/n",RetValue);
 getchar();
}