Please find and correct the error in my c++ program. "Linker Error: Undefined symbol

[bugmenot]

Please find and correct the error in my c++ program. "Linker Error: Undefined symbol _main in module c0.ASM"
The program is for transfering content of one file to another.

#include
#include
#include
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)";
cin>>ch;
}
outf.close();
}
void student::transfer()
{
ofstream outf;
ifstream inf;
inf.open("mark.dat");
inf.open("trans.dat");
while(inf)
{
inf.read((char*)&obj,sizeof(obj));
outf.write((char*)&obj,sizeof(obj));
}
outf.close();
inf.close();
}
void student::output()
{
ifstream inf;
inf.open("trans.dat");
while(inf)
{
inf.read((char*)&obj,sizeof(obj));
cout<<"Rollno"<

[bugmenot]

think i got this from my friend

void main()
{
student obj;
obj.input();
obj.transfer();
obj.output();
getch();
}

He told to put it at last but hwo do i do that?

[bugmenot]

I found the error and corrected it.
#include
#include
#include
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)";
cin>>ch;
}
outf.close();
}
void student::transfer()
{
ofstream outf;
ifstream inf;
inf.open("mark.dat");
inf.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<<"Rollno"<

[bugmenot]

I still have another problem. That is when the while loop asks continue(y/n)
When i enter n it just stuck there.

I need to make the program error free urgently. Please reply with solution. I use borland turbo c++ 3

[toadily8]

char str[] = 'stop';
if (isupper (str) =="STOP")
exit(0);