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();}
 void REV(UserList &L)
 {cerr<<"功能未定义"<<endl;Sleep();}
 void SEE(UserList &L)
 {
     cout<<"表："<<endl;
     for(int i=;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 :flag=false;break;
             case :ADD(L);break;
             case :DEL(L);break;
             case :REV(L);break;
             case :SEE(L);break;
             default:break;
         }
     }
     Sleep();
     return ;
 }

Demo9.1.cpp

/*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[];
         N=;
         nMax=;
     //    FileName=Fn;
         FileName="D:\\#\\Users.dat";
         readFile();
     }
     //
     bool readFile()
     {
         ifstream fin(FileName.c_str(),ios::binary);
         if(!fin)
             return false;
         fin.seekg(,ios::end);
         int FileLen=fin.tellg(),len=sizeof(User);
         fin.seekg(,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-;
         }//'else-重分配内存'或'使用vector容器'解决数据溢出
         return -;
     }
     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;}
 };

UserList.h

/*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)
     {}
 };

User.h

后序慢慢补充