lease find and correct the error in my c++ program.

Please correct the error in my program. When i run the program on turbo c++ 3, it output 3 times. Also When i enter more than 1 entry only the last entry is outputted. Also it is outputted 3 times. Please run the program and see.

#include<fstream.h>
#include<iostream.h>
#include<conio.h>
class student
{
int rollno;
char name[20];
int tm;
public:
void input();
void transfer();
void output();
}
obj;
void student::input()
{
char ch='y';
ofstream outf;
outf.open("mark.dat");
while(ch=='y')
{
cout<<"Enter rollno, name and mark";
cin>>rollno>>name>>tm;
outf.write((char*)&obj,sizeof(obj));
cout<<"Wish to enter more(Y/N)?\n";
cin>>ch;
}
outf.close();
}
void student::transfer()
{
ofstream outf;
ifstream inf;
inf.open("mark.dat");
outf.open("trans.dat");
while(inf)
{
inf.read((char*)&obj,sizeof(obj));
outf.write((char*)&obj,sizeof(obj));
}
outf.close();
inf.close();
}
void student:utput()
{
ifstream inf;
inf.open("trans.dat");
while(inf)
{
inf.read((char*)&obj,sizeof(obj));
cout<<"\nRollno "<<rollno;
cout<<"\nName "<<name;
cout<<"\nTotal "<<tm;
}
inf.close();
}
void main()
{
clrscr();
student obj;
obj.input();
obj.transfer();
obj.output();
getch();
}

 

have tried to intend it.

Thank you very much for taking time. I am from India and here we learn about only basics of c++ and our syllabus is based on turbo c++ 3. So i use turbo c++ and i don't know much about c++ programing. So i cannot implement instructions you give on modern c++.

I tried new changes. But i still have some little problems. The program is to transfer content of one file to another. When i input only one entry, the program works. But when more than one entry is used it out puts only 1 or 2. Kindly please correct the problem.

Here is the new code by correcting the previous errors.

#include<fstream.h>
#include<iostream.h>
#include<conio.h>
class student
{
int rollno;
char name[20];
int tm;
public:
void input();
void transfer();
void output();
};
void student::input()
{
char ch='y';
ofstream outf;
outf.open("mark.dat");
while(ch=='y')
{
cout<<"Enter rollno, name and mark\n";
cin>>rollno>>name>>tm;
outf.write((char*)this,sizeof(student));
cout<<"Wish to enter more(Y/N)?\n";
cin>>ch;
}
outf.close();
}
void student::transfer()
{
ofstream outf;
ifstream inf;
inf.open("mark.dat");
outf.open("trans.dat");
while( inf.read(( char* )this,sizeof(student)))
{
outf.write(( char* )this,sizeof( student ) );
}
outf.close();
inf.close();
}
void student:utput()
{
ifstream inf;
inf.open("trans.dat");
while (inf.read((char*)this, sizeof(student)))
{
inf.read(( char* )this,sizeof( student ) );
cout<<"\nRollno "<<rollno;
cout<<"\tName "<<name;
cout<<"\tTotal "<<tm<<'\n';
}
inf.close();
}
void main()
{
clrscr();
student obj;
obj.input();
obj.transfer();
obj.output();
getch();
} 

Code (markup):

 

Why are you reading from the file twice in ur while loop ?

 

I don't know very much in c++. Anyone please correct it for me.

 

I got all the program correctly here is it.

#include<fstream.h>
#include<iostream.h>
#include<conio.h>
class student
{
int rollno;
char name[20];
int tm;
public:
	void input();
	void transfer();
	void output();
	};
void student::input()
{
char ch='y';
ofstream outf;
outf.open("mark.dat");
while(ch=='y')
{
cout<<"Enter rollno, name and mark\n";
cin>>rollno>>name>>tm;
outf.write((char*)this,sizeof(student));
cout<<"Wish to enter more(Y/N)?\n";
cin>>ch;
}
outf.close();
}
void student::transfer()
{
ofstream outf;
ifstream inf;
inf.open("mark.dat");
outf.open("trans.dat");
while( inf.read(( char* )this,sizeof(student))) 
{
outf.write(( char* )this,sizeof( student ) );
}
outf.close();
inf.close();
}
void student::output()
{
ifstream inf;
inf.open("trans.dat");
while (inf.read((char*)this, sizeof(student)))
{
cout<<"\nRollno "<<rollno;
cout<<"\tName "<<name;
cout<<"\tTotal "<<tm<<'\n';
}
inf.close();
}
void main()
{
clrscr();
student obj;
obj.input();
obj.transfer();
obj.output();
getch();
}

Code (markup):