文件处理类对象
File handling class object
这是一个C++实现离线消息传递系统的程序。首先，用户必须通过选择用户名和密码来注册帐户。然后，他们可以向其他用户发送和接收消息。
我已经编写了程序，但似乎有一些逻辑错误。
我在注册时将用户详细信息写入文件电子邮件中。数据作为对象写入文件。
假设我注册了 3 个帐户。 但我无法登录 IE。我无法验证登录并将控制权传递给signin();
为了解决错误，我创建了一个显示文件电子邮件内容的print()函数。
我已将其放置在登录身份验证部分之前，以查看是否存在数据记录
但是，不会显示记录。
在解决此问题之前，我无法测试代码的其他部分。
我认为可能是错误原因的部分代码：
#include<fstream.h>
#include<conio.h>
#include<string.h>
#include<process.h>
#include<stdio.h>
int user; // to keep a track of no. of users
class mail
{
public:
char un[25]; // user name
char pd[25]; // passsword
int ino; // no. of inbox messages
int sno; //no.of sent messags
char isbj[25][25];
char ssbj[25][25];
char imsg[25][50];
char smsg[25][50]; // character array to store inbox and sent messages respecvly
void reg(); // func to sign up
void signin();
mail()
{
}
~mail()
{
}
};
void print();
void print() // for testing purpose. retrieving data in the file
{
mail o;
cout<<"nRunning print func();";
ifstream filein;
filein.open("email",ios::in|ios::binary);
if(!filein)
{
cout<<"Unable to open file to readn";
}
else
{
filein.seekg(0);
filein.read((char *)&o,sizeof(o));
while(filein)
{
puts(o.un);
puts(o.pd);
cout<<o.ino<<" "<<o.sno;
filein.read((char *)&o,sizeof(o));
}
getch();
}
}
void mail::reg() // sign up function
{
clrscr();
cout<<"Enter user name ( enter unique name )n";
gets(un);
cout<<"Enter passwordn";
gets(pd);
ofstream filout;
filout.open("email",ios::app|ios::binary);
if(!filout)
{
cout<<"cannot open filen";
}
else
{
ino=-1;
sno=-1; // initialising no. of sent and inbox msgs as 0 on regtrn
filout.write((char *)&this,sizeof(this));
filout.close();
}
cout<<"You are now registered. Plz loginn";
getch();
} // end of sign up or register func
void mail::signin()
{
.
.
.
} // end of signin
void screen(void);
void signup(void);
void main()
{
clrscr();
char usrnm[25],pwd[25],s[25],c;
int i;
m:
clrscr();
screen();
gotoxy(30,4);
c=getch();
if(c=='i'||c=='I') //if user opts to sign in
{
gotoxy(62,11);
gets(usrnm);
gotoxy(62,13);
for(i=0;i< 25;i++) // getting password
{
if( i < 0)
i=0;
pwd[i]=getch();
if(pwd[i]=='b')
{
i-=2;
cout<<"b b";
continue;
}
if(pwd[i]=='r')
break;
cout<<"*";
}
pwd[i]=' ';
clrscr(); // pwd now contains password for sign in
print();
int f;
{ // local block
mail obj;
ifstream filein;
filein.open("email",ios::in|ios::binary); // to read records from file and authenticating the user
if(!filein)
{
cout<<"Unable to open file to readn";
}
else
{
filein.seekg(0);
filein.read((char *)&obj,sizeof(obj));
while(filein)
{
if(strcmp(usrnm,obj.un)==0)
{
f=1;
if(strcmp(pwd,obj.pd)==0)
{
obj.signin(); // user authenticated. now transfering control
break;
}
else
{
cout<<"wrong passwordn";
getch();
break;
}
} // end of if
else
{
}
filein.read((char *)&obj,sizeof(obj));
} // end of while
filein.close();
} // end of else
}
if(f==0)
cout<<"Wrong username or passwordn";
getch();
goto m;
}
else if(c=='s'||c=='S') // user opts to sign up
{
signup();
getch();
goto m;
}
else if(c=='e'||c=='E') // user choose to exit
exit(0);
else
{
clrscr();
cout<<"you have entered a wrong key. please check and try againn";
getch();
goto m;
}
} //end of main
void signup() // sign up function
{
int t;
clrscr();
{
mail obj;
ifstream filin;
filin.open("user.txt",ios::ate); // a file to store the no. of currently registered user. THIS IS FOR FUTURE USE
if(!filin)
{
cout<<"cannot open filen";
}
else
{
filin.seekg(0);
filin>>t;
}
filin.close();
user=t;
++user; // incrementing no. users
ofstream filout;
filout.open("user.txt",ios::out);
if(!filout)
{
cout<<"cannot open filen";
}
else
{
filout.seekp(0);
filout<<user; //Updating user
}
filin.close();
obj.reg();
} // end of block
return;
} // end of sign up
void screen() // function for login screen
{
.
.
}
完整代码：
#include<fstream.h>
#include<conio.h>
#include<string.h>
#include<process.h>
#include<stdio.h>
int user; // to keep a track of no. of users
class mail
{
public:
char un[25]; // user name
char pd[25]; // passsword
int ino; // no. of inbox messages
int sno; //no.of sent messags
char isbj[25][25];
char ssbj[25][25];
char imsg[25][50];
char smsg[25][50]; // character array to store inbox and sent messages respecvly
void reg(); // func to sign up
void signin();
mail()
{
}
~mail()
{
}
};
void print();
void print() // for testing. retrieving data in the file
{
mail o;
cout<<"nRunning print func();";
ifstream filein;
filein.open("email",ios::in|ios::binary);
if(!filein)
{
cout<<"Unable to open file to readn";
}
else
{
filein.seekg(0);
filein.read((char *)&o,sizeof(o));
while(filein)
{
puts(o.un);
puts(o.pd);
cout<<o.ino<<" "<<o.sno;
filein.read((char *)&o,sizeof(o));
}
getch();
}
}
void mail::reg() // sign up function
{
clrscr();
cout<<"Enter user name ( enter unique name )n";
gets(un);
cout<<"Enter passwordn";
gets(pd);
ofstream filout;
filout.open("email",ios::app|ios::binary);
if(!filout)
{
cout<<"cannot open filen";
}
else
{
ino=-1;
sno=-1; // initialising no. of sent and inbox msgs as 0 on regtrn
filout.write((char *)&this,sizeof(this));
filout.close();
}
cout<<"You are now registered. Plz loginn";
getch();
} // end of sign up or register func
void mail::signin()
{
int f,i;
char subj[25],message[50],usrnm[25]; // temporary varibles to store subject,message and username
start:
clrscr();
cout<<"1.compose n2.inbox n3.Sentn4.logout";
cout<<"nEnter ur choicen";
int ch;
cin>>ch;
switch(ch)
{
case 1: // switch for compose message
cout<<"enter usernamen";
gets(usrnm);
{ // beginning of local loop
mail temp;
ifstream filein;
filein.open("email",ios::in|ios::binary);
if(!filein)
{
cout<<"Unable to open file to readn";
}
else
{
filein.read((char *)&temp,sizeof(temp));
while(filein)
{
if(strcmp(usrnm,temp.un)==0)
{
cout<<" User name validn";
f=1;
cout<<"Enter subjectn";
gets(subj);
cout<<"Enter messagen";
gets(message);
temp.ino++;
strcpy(temp.isbj[temp.ino],subj);
strcpy(temp.imsg[temp.ino],message); // copying message to recepient inbox
sno++;
strcpy(ssbj[sno],subj);
strcpy(smsg[sno],message); // copying messages to sender sent folder
cout<<"Your message has been sent successfullyn";
break;
}
else // to avoid if else mismatch
{
}
filein.read((char *)&temp,sizeof(temp));
} // end of while
}
filein.close();
mail temp1;
long pos; // below code modifies current users object
fstream fio("email",ios::in|ios::out|ios::binary);
pos=fio.tellg();
fio.read((char*)&temp1,sizeof(temp1));
while(fio)
{
if(strcmp(un,temp1.un)==0)
{
fio.seekg(pos);
fio.write((char*)&this,sizeof(this));
break;
}
pos=fio.tellg();
fio.read((char*)&temp1,sizeof(temp1));
} //end of while
fio.close();
mail temp2; // below code modifies recipients object
fio.open("email",ios::in|ios::out|ios::binary);
pos=fio.tellg();
fio.read((char*)&temp2,sizeof(temp2));
while(fio)
{
if(strcmp(temp.un,temp2.un)==0)
{
fio.seekg(pos);
fio.write((char*)&temp,sizeof(temp));
break;
}
pos=fio.tellg();
fio.read((char*)&temp2,sizeof(temp2));
} // end of while
fio.close();
} // end of block
if(f==0)
cout<<"invalid user. Please enter a valid user namen";
getch();
break;
case 2:
if(ino<0)
cout<<"There are no messages in your inboxn";
else
{
for(i=0;i<=ino;i++)
{
cout<<"nMessage "<<i+1<<"n"; // printing inbox messages
puts(isbj[i]);
puts(imsg[i]);
}
}
getch();
break;
case 3:
if(sno<0)
cout<<"There are no sent messagesn";
else
{
for(i=0;i<=sno;i++)
{
cout<<"nMessage "<<i+1<<"n"; // printing sent messages
puts(ssbj[i]);
puts(smsg[i]);
}
}
getch();
break;
case 4:
cout<<"Logout sucessn";
return;
default : cout<<"wrong choicen";
} // end of switch
goto start;
} // end of signin
void screen(void);
void signup(void);
void main()
{
clrscr();
char usrnm[25],pwd[25],s[25],c;
int i;
m:
clrscr();
screen();
gotoxy(30,4);
c=getch();
if(c=='i'||c=='I') //if user opts to sign in
{
gotoxy(62,11);
gets(usrnm);
gotoxy(62,13);
for(i=0;i< 25;i++) // getting password
{
if( i < 0)
i=0;
pwd[i]=getch();
if(pwd[i]=='b')
{
i-=2;
cout<<"b b";
continue;
}
if(pwd[i]=='r')
break;
cout<<"*";
}
pwd[i]=' ';
clrscr(); // pwd now contains password for sign in
print();
int f;
{ // local block
mail obj;
ifstream filein;
filein.open("email",ios::in|ios::binary); // to read records from file and authenticating the user
if(!filein)
{
cout<<"Unable to open file to readn";
}
else
{
filein.seekg(0);
filein.read((char *)&obj,sizeof(obj));
while(filein)
{
if(strcmp(usrnm,obj.un)==0)
{
f=1;
if(strcmp(pwd,obj.pd)==0)
{
obj.signin(); // user authenticated. now transfering control
break;
}
else
{
cout<<"wrong passwordn";
getch();
break;
}
} // end of if
else
{
}
filein.read((char *)&obj,sizeof(obj));
} // end of while
filein.close();
} // end of else
}
if(f==0)
cout<<"Wrong username or passwordn";
getch();
goto m;
}
else if(c=='s'||c=='S') // user opts to sign up
{
signup();
getch();
goto m;
}
else if(c=='e'||c=='E') // user choose to exit
exit(0);
else
{
clrscr();
cout<<"you have entered a wrong key. please check and try againn";
getch();
goto m;
}
} //end of main
void signup() // sign up function
{
int t;
clrscr();
{
mail obj;
ifstream filin;
filin.open("user.txt",ios::ate); // a file to store the no. of currently registered user. THIS IS FOR FUTURE USE
if(!filin)
{
cout<<"cannot open filen";
}
else
{
filin.seekg(0);
filin>>t;
}
filin.close();
user=t;
++user; // incrementing no. users
ofstream filout;
filout.open("user.txt",ios::out);
if(!filout)
{
cout<<"cannot open filen";
}
else
{
filout.seekp(0);
filout<<user; //Updating user
}
filin.close();
obj.reg();
} // end of block
return;
} // end of sign up
void screen() // function for login screen
{
int i;
for(i=0;i<80;i++)
cout<<"*";
cout<<" SuperMail New to SuperMial ? Create an Account ";
for(i=0;i<80;i++)
cout<<"*";
cout<<" Press S To Sign up Already have a account Press I to sign in";
for(i=0;i<80;i++)
cout<<"-";
gotoxy(1,6);
cout<<"nnnn Super mail is built on the idea that n it can be more intuitive,efficient and n useful and may be even fun:nn Lots of spacenn Less spam";
gotoxy(1,22);
for(i=0;i<80;i++)
cout<<"-";
gotoxy(32,23);
cout<<"PRESS E TO EXIT";
gotoxy(1,24);
for(i=0;i<80;i++)
cout<<"-";
gotoxy(50,10);
cout<<"-------------------------------";
gotoxy(50,11);
cout<<"| USERNAME : |";
gotoxy(50,12);
cout<<"-------------------------------";
gotoxy(50,13);
cout<<"| PASSWORD : |";
gotoxy(50,14);
cout<<"-------------------------------";
}
我没有通读所有代码，但一个问题是
filout.write((char *)&this,sizeof(this));
this是一个指针，因此上面的代码将类实例的地址写入文件。 您可以使用
filout.write((char*)this,sizeof(*this));
我希望这也会写出一些你不想要/不需要的数据，例如逆向表的地址。 最好显式保留您关心的类成员。
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