>anyway the problem still exist with the same errors as before
What errors are you getting?
1) Did the code compile? If not, what are the error messages?
2) If the code compiled, what happens when you run the program?
3) Post a copy of your E:\\mark.txt file
>fin.open("E://mark.txt");
It may not matter, but your forward slashes should be backslashes:
fin.open("E:\\mark.txt");
