C++的IO操作

写对象
#include <fstream.h>
#include <stdio.h>
const int LEN=80;

class Book
{
 public:
  void getdata()
  {
   cout<<"Enter book title: ";
   cin>>title;
   cout<<"Enter book author: ";
   cin>>author;
   cout<<"Enter book sold per month: ";
   cin>>numsold;
  }
 private:
 char title[LEN];
 char author[LEN];
 int numsold;
};

int main(int argc, char *argv[])
{
 ofstream output("IO.txt");
 Book A;
 char ch;
 do
 {
  A.getdata();
  output.write((char *) &A,sizeof(A));
  cout<<"Enter another one? (y/n): ";
  cin>>ch;
 }while(ch=='y');
 
 return 0;
}
=========================================================
读写 Vector
#include <iostream>
#include <fstream>
#include <iterator>
#include <vector>
#include <algorithm>

using namespace std;

template<typename T>
struct Point {
    T x,y;
    explicit Point(const T& x=0, const T& y=0) : x(x),y(y) {}
};

template<typename T>
ostream& operator<< (ostream& os, const Point<T>& p)
{
    os << ' ' << p.x << ' ' << p.y;
    return os;
}

template<typename T>
istream& operator>> (istream& is, Point<T>& p)
{
    is >> p.x >> p.y;
    return is;
}

int main()
{
    //从文件中读出数据
    ifstream fin("save.txt");
    vector<Point<int> > v;
    copy(istream_iterator<Point<int> >(fin),
        istream_iterator<Point<int> >(),
            back_inserter(v) );
    //打印数据
    copy(v.begin(), v.end(),
        ostream_iterator<Point<int> >(cout,"/n"));
    //存入文件
    ofstream fout("out.txt");
    copy(v.begin(), v.end(),
        ostream_iterator<Point<int> >(fout,"/n"));

    cout << "Press ENTER to exit.";
    cin.get();
}
 
////////////////////////////////////

#include <iostream.
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;

int main()
{ 
    ifstream fopen("open.txt");
    ofstream fsave('save.txt");
    if(!fopen||!fsave)
    {
         cerr<<"unable to open file "<<endl;
         return -1;
     }
     // 将文件数据读到vector
     vector<int> v( istream_iterator<int>(fopen), istream_iterator() );
     //存入文件
     copy( v.begin(), v.end(), ostream_iterator<int>(fsave, " ") ); 
  
     return 0;
}

================================================

基本读写操作
#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 opened!"<<endl;
  abort();
 }

 outstuf<<"This is a file of students .../n";
 cout<<"Input the number,name,and score : (Enter Ctrl+z to end input)/n?";
 while(cin>>number>>name>>score)
 {
  outstuf<<number<<'/t'<<'/"'<<name<<'/"'<<'/t'<<score<<'/n';
  cout<<'?';
 }
 outstuf.close();
 return 0;
}

=============================================================

格式读取
#include <iostream>
#include <fstream>
using namespace std;

void main()
{
    char *lp[2];
    int i = 0;
    char s[10]="S";
    ifstream in("in.txt");
    while(!in.eof())
    {
 char order[10];
 char content1[30];
 char content2[30];
 char other[10];
 in.getline(order,sizeof(order),'(');
 if(strcmp(s,order)==0)
 {
     in.getline(content1,sizeof(content1),',');
     in.getline(content2,sizeof(content2),')');
     i=*content1-48;
     lp[i]=content2;
     cout<<"lp["<<i<<"] "<<lp[i]<<endl;
 }
 in.getline(other,sizeof(other),'/n');
    }
    in.close();
}

==================================================

链表，IO
#include <iostream.h>
#include <fstream.h>

struct data
{
 int id;//登记号
 int num;//书分类号
 char name[10];
 float price;
 char date[10];
 char press[20];
 int buyn;
 int lendn;
 data *next;
};

void show(ofstream outf, data *head)  //显示内容
{
 data *p;
 p=head;
 outf<<"/nNow ,Thes records are:/n";
 if (head!=NULL)
  do
  {
   outf<<"id:   "<<p->id<<"/n"
    <<"num:  "<<p->num<<"/t"
    <<"name: "<<p->name<<"/t"
    <<"price:"<<p->price<<"/t"
    <<"date: "<<p->date<<endl
    <<"press:"<<p->press<<endl
    <<"buyn: "<<p->buyn<<"/t"
    <<"lendn:"<<p->lendn<<endl<<endl;
   p=p->next;
  }while (p!=NULL);
}

data *insert(data *head,data *da)//输入数据
{
 data *p0, *p1, *p2;
 p1=head;
 p0=da;
 if (head == NULL)
 {
  head = p0;
  p0->next=NULL;
 }
 else
 {
  while ((p0->id > p1->id)&&p1->next!=NULL)
  {
   p2 = p1;
   p1 = p1->next;
  }
  if (p0->id <= p1->id)
  {
   if (head == p1)
   {
    head = p0;
    p0->next = p1;
   }
   else
   {
    p2->next = p0;
    p0->next=p1;
   }
  }
  else
  {
   p1->next = p0;
   p0->next = NULL;
  }
 }
 return head;
}

void main()
{
 ofstream outf("book.txt");
 if (!outf)
  cout<<"can't open file./n";
 data *head,*p0;
 int n=0;
 head = NULL;
 for (;;)
 {
  n++; 
  cout<<"Input the "<<n<<" data:/n";
  p0=new data;
  cout<<"id:   ";
  cin>>p0->id;
  if (p0->id==0)
  {
   delete [] p0;
   break;
  }
  cout<<"num:  ";  cin>>p0->num;
  cout<<"name: ";  cin>>p0->name;
  cout<<"price:";  cin>>p0->price;
  cout<<"data: ";  cin>>p0->date;
  cout<<"press:";  cin>>p0->press;
  cout<<"buyn: ";  cin>>p0->buyn;
  cout<<"lendn:";  cin>>p0->lendn; ;

  head = insert(head,p0); //调用函数插入数据

  cout<<endl;
 }

 show(outf, head);  //调用函数把数据写进文件
 outf.close();

 ifstream inf("book.txt");  //输出到显示器
 if (!inf)
  cout<<"can't open the file./n";
 char c;
 cout<<"/n/nthe bookdata is:/n/n";
 while (inf.get(c))//显示文件的数据到显示器
  cout<<c;
 cout<<endl;
 inf.close();
}