文件操作写入和读出结构体--修改文件信息

// file3.cpp : 定义控制台应用程序的入口点。
//
//
#include "stdafx.h"
#include <fstream>
#include <iostream>
using namespace std;
struct Student{
char name[20];
int num;
};
int addInFile()
{
ofstream outFile("botao.dat",ios::out|ios::binary);  //定义文件输出流   文件不存在时创建文件
//对文件打开错误时的操作
if(!outFile)
{
cout<<"The file open error!"<<endl;
return 0;
}
else        //文件正常打开时，进行相应的处理
{
Student *s=new Student;
cout<<"输入学生姓名：";
cin>>s->name;
cout<<"输入学生学号：";
cin>>s->num;
outFile.write((char*)s,sizeof(Student));   //文件输出流向文件中写入student信息
}
outFile.close();   //关闭输出流
return 1;
}
int myReadFile()
{
ifstream inFile("botao.dat",ios::in|ios::binary);   //文件输入流  将文件中的student信息读出到屏幕上
//对文件打开错误时的操作
if(!inFile)
{
cout<<"The inFile open error!"<<endl;
return 0;
}
else
{
Student *s=new Student;
inFile.read((char*)s,sizeof(Student));
cout<<"姓名："<<s->name<<endl;
cout<<"学号："<<s->num<<endl;
}
inFile.close();       //关闭输入流
}
void addCustomers(char *identityCard,int number,int isExist)        //      添加顾客信息  想总的顾客信息索引表中添加数据
{
ifstream inf("botao.dat",ios::in|ios::binary);
if(!inf)
{
cout<<"文件不存在，正在创建……"<<endl;
ofstream outf("botao.dat",ios::out|ios::binary);
outf.close();
}
inf.close();
fstream outFile("botao.dat",ios::app|ios::in|ios::binary);
Student *index=new Student;
if(!outFile)
{
cout<<"Open Error!"<<endl;
//exit(1);
}
else
{
if(isExist==0)      //如果此顾客还没有在此航空公司买过票
{
outFile.seekp(ios::end);    //文件指针重新定位
index->num=0;
strcpy(index->name,identityCard);
index->num=number;
outFile.write((char*)index,sizeof(Student));  //*****将信息写入到文件中
cout<<"index->name:"<<index->name<<endl;
cout<<"index ->num:"<<index->num<<endl;
//outFile.flush();      //将缓冲中数据刷如到文件中
}
else        //如果此顾客已经存在
{
while(outFile.read((char*)index,sizeof(Student)))   //
{
if(strcmp(identityCard,index->name)==0)
{
cout<<"指针移动前：--------"<<outFile.tellg()<<endl;
outFile.seekg(-(long)sizeof(Student),ios::cur);
cout<<"指针移动后：--------"<<outFile.tellg()<<endl;
index->num=0;
strcpy(index->name,identityCard);
index->num=number;
cout<<"index->name:"<<index->name<<endl;
cout<<"index->num:"<<index->num<<endl;
if(outFile.write((char*)index,sizeof(Student)))  //*****将修改后信息写入到文件中
cout<<"cheng  gong        ________________________"<<endl;
//myReadFile();
ifstream iinFile("botao.dat",ios::in|ios::binary);
//Student *s=new Student;
iinFile.seekg(-(long)sizeof(Student),ios::cur); //将指针定位到修改信息后的结构体前面
iinFile.read((char*)index,sizeof(Student));
cout<<"姓名："<<index->name<<endl;
cout<<"学号："<<index->num<<endl;
iinFile.close();
break;
}
index=new Student;
}
}
}
//delete index;
outFile.close();
}
int main()
{
cout<<"The main .............."<<endl;
//addInFile();  //添加结构体
addCustomers("botao1",1,1);
//myReadFile();  //读取结构体
return 0;
}