使用c ++

Question

将一个班级学生的标记和滚动详细信息写入文件中。输出仅包含最后输入的数据。为什么会这样？

#include<fstream.h>
int main()
{
 ofstream fout;
 fout.open("File1",ios::out);
 char cch;
 fout<<"ROLLNO\t"<<"MARKS"<<"\n";
 int rollno,marks;
 do
 {
  cout<<"Enter the rollno1";
  cin>>rollno;
  cout<<"Enter the marks";
  cin>>marks;
  fout<<rollno<<"\t"<<marks<<"\n";
  cout<<"Do you want to insert more?" ;
  cin>>cch;
 }
while(cch=='y');
 fout.close();

 ifstream fin;
 char ch;
 fin.open("File1",ios::in);
 fin.seekg(0);
 fin.tellg();
 while(fin)
 {
      fin>>rollno;
       fin>>marks;
      cout<<rollno<<"\t"<<marks<<"\n";
  }
fin.close();
return 0;
}

请帮我找到错误。