文件操作

/*#include<fstream>
#include<iostream>
using namespace std;
int main()
{
int i,j;
  fstream f;
  f.open("d:\\DATA.dat",ios::out|ios::binary);
  for(i=1;i<=10;i++)
  {
f.write((char*)&i,sizeof(int));
  }
  f.close();
  f.open("d:\\DATA.dat",ios::in|ios::out|ios::binary);
  for(i=1;i<10;i++)
  {
f.seekg(long(sizeof(int)*i));
f.read((char*)&j,sizeof(int));
if (j%2)
{
j+=10;
f.seekp(-long(sizeof(int)),ios::cur);
f.write((char*)&j,sizeof(int));
}
  }
  f.seekg(long(sizeof(int)*10));
  for(i=91;i<=95;i++)
  {
    f.write((char*)&i,sizeof(int));
  }
  f.seekg(0,ios::beg);
  for(i=0;i<15;i++)
  {
 f.read((char*)&j,sizeof(int));
 cout<<j<<" ";
  }
  cout<<endl;
  f.close();
}*/
/*
#include<iostream>
#include<fstream>
using namespace std;
int main()
{
   char fileName[30],name[30];
   int number,score;
   ofstream outstuf;
   cout<<"please input the name of students file:\n";
   cin>>fileName;
   outstuf.open(fileName,ios::out);
   if(!outstuf)
   {
     cerr<<"File could not be open"<<endl;
abort();
   }
   outstuf<<"This is a file of students\n";
   cout<<"Input the number,name,and score\n?";
   while(cin>>number>>name>>score)
   {
  outstuf<<number<<' '<<name<<' '<<score<<'\n';
  cout<<"?";
   }
   outstuf.close();
}*/
/*
#include<iostream>
#include<fstream>
using namespace std;
struct student
{
  int number;
  char name[30];
  int score;
};
const student mark={ 0,"noName\0",0 };
int main()
{
  char s[80];
  student stu;
  ifstream instuf("d:\\students.txt",ios::in);
  ofstream outstuf("d:\\students.dat",ios::out|ios::binary);
  //写进二进制数据文件
  if(!instuf|!outstuf)
  {
 cerr<<"File could not be open."<<endl;
 abort();
  }
  instuf.getline(s,80);
  while(instuf>>stu.number>>stu.name>>stu.score)
  {
cout<<stu.number<<'\t'<<stu.name<<'\t'<<stu.score<<'\n';
outstuf.write((char*)&stu,sizeof(student));
  }
  outstuf.write((char*)&mark,sizeof(student));
  instuf.close();
  outstuf.close();
}*/
#include<iostream>
#include<fstream>
using namespace std;


struct student
{
int number;
char name[30];
int score;
};
int main()
{
  student stu;
  int n=0,max,min,total=0;
  double ave;
  ifstream instuf("d:\\students.dat",ios::in);
  if(!instuf)
  {
 cerr<<"File could not be open."<<endl;
 abort();
  }
  do 
  {
 instuf.read((char*)&stu,sizeof(stu));
 if(stu.number!=0)
 {
 cout<<stu.number<<'\t'<<stu.name<<'\t'<<stu.score<<'\n';
 if(n==0)
 {
  max =min=stu.score;
 }
 else
 {
 if(stu.score > max) max =stu.score;
 if(stu.score <min) min=stu.score;
 }
 total+=stu.score;
 n++;
 }
  } while (instuf&&stu.number!=0);
  cout<<"总人数："<<n<<endl;
  ave=double(total)/n;
  cout<<"最高分："<<max<<endl;
  cout<<"最低分："<<min<<endl;
  cout<<"平均分："<<ave<<endl;
  instuf.close();
}