C++二进制文件读写

简单二进制文件读写，多文件

/*Demo9.1.cpp*/

#include <iostream>
#include <fstream>
#include <string>
#include <windows.h>
#include "UserList.h"
using namespace std;

int showMain()
{
    system("cls");
    cout<<"1.增加"<<endl;
    cout<<"2.删除"<<endl;
    cout<<"3.修改"<<endl;
    cout<<"4.查询"<<endl;
    cout<<"0.退出"<<endl;
    cout<<"请选择：";
    cin.sync();
    int c;
    cin>>c;
    return c;
}

void ADD(UserList &L)
{
    cout<<"input:"<<endl;
    string id,name,password;
    cin>>id>>name>>password;
    User u(id,name,password);
    L.Add(u);
}
void DEL(UserList &L)
{cerr<<"功能未定义"<<endl;Sleep(512);}
void REV(UserList &L)
{cerr<<"功能未定义"<<endl;Sleep(512);}
void SEE(UserList &L)
{
    cout<<"表："<<endl;
    for(int i=0;i<L.getN();i++)
        L.display(i);
    cout<<endl;
    system("pause");
}

int main()
{
    UserList L;
//    User admin("0","admin","admin");
//    L.Add(admin);
    bool flag=true;
    while(flag)
    {
        switch(showMain())
        {
            case 0:flag=false;break;
            case 1:ADD(L);break;
            case 2:DEL(L);break;
            case 3:REV(L);break;
            case 4:SEE(L);break;
            default:break;
        }
    }
    Sleep(256);
    return 0;
}

/*UserList.h*/

#include <fstream>
#include "User.h"
using namespace std;

class UserList
{
protected:
    User *List;
    int N,nMax;
    string FileName;
public:
    UserList(/*string Fn=""*/)
    {
        List=new User[32];
        N=0;
        nMax=32;
    //    FileName=Fn;
        FileName="D:\#\Users.dat";
        readFile();
    }
    //
    bool readFile()
    {
        ifstream fin(FileName.c_str(),ios::binary);
        if(!fin)
            return false;
        fin.seekg(0,ios::end);
        int FileLen=fin.tellg(),len=sizeof(User);
        fin.seekg(0,ios::beg);
        fin.read((char *)List,(N = FileLen<nMax*len?FileLen/len:nMax)*len);
        fin.close();
        /*
        printf("*%d*",N);
        for(int i=0;i<N;i++)
            display(i);
        cout<<endl;
        */
        return true;
    }
    int Add(User u)
    {
        if(N<nMax)
        {
            List[N]=u;
            ofstream fout(FileName.c_str(),ios::app|ios::binary);
            int len=sizeof(User);
            fout.seekp((N)*len);
            fout.write((char *)&List[N],len);
            fout.close();

            N++;
            return N-1;
        }//'else-重分配内存'或'使用vector容器'解决数据溢出
        return -1;
    }
    void idFind(string id)
    {
    }
    void nameFind(string name)
    {
    }
    void display(int i)
    {cout<<"ID:"<<List[i].id<<endl<<"Name:"<<List[i].name<<endl<<"Password:"<<List[i].password<<endl;}
    int getN()
    {return N;}
};

/*User.h*/

#include <iostream>
#include <string>
using namespace std;

class User
{
    friend class UserList;
protected:
    string id;
    string name;
    string password;
public:
    User(string id="",string name="",string password=""):id(id),name(name),password(password)
    {}
};

后序慢慢补充