文件包含问题

#include"file1.h"
#include"file2.h"

{float V;
V=(3/4)*PI*r*r*r;
}
{float  S;
S=4*PI*r*r;
}
#include<stdio.h>
#define PI  3.1415926;
float main()
{float  r,PI;
  cout<<"input  the  munber  of  r="<<endl;
  cout<<V <<S <<endl;
运行结果出错，“Cannot open include file: 'file1.h': No such file or directory“，菜鸟一只，急求解答