Thread: No operator matches "[]" these operands And error C2248

I'm getting No operator matches "[]" these operands

and this error that I have no clue about :\program files (x86)\microsoft visual studio 10.0\vc\include\fstream(1116): error C2248: 'std::basic_ios<_Elem,_Traits>::basic_ios' : cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>'

Code:

#include <string>
#include <iostream>
#include <fstream>
#include <iomanip>
#define SIZE 20    
using namespace std ; 
struct Students{
    ifstream Fin;
    ofstream Fout;
    float Units, GPA, Total_Units, Avg_GPA, Mega_Units, Cyan, Mega_Cyan, GradeK; 
    long  ID;
    string  First_Name, Last_Name , name, letter, Grade;
};

void print_OList(Students List[], int size);
void print_O(Students Temp, int size);
float assign_grade(Students &Temp, int size);
void Process_List(Students List[], int size, float Cyan);
void Read_Stu(Students &Temp, ifstream &Fin, int size);
void Calc_GPA(Students &Temp) ;
int read_O(Students List[], int safe);
void Intro();
int main() {
    Students    List[SIZE];
    string letter;
    float Cyan = 0;
    int    size = 0, j = 0;
    Intro();
    size = read_O(List,SIZE);
    if (letter == "O" || letter == "o")
            {
            read_O(List, SIZE);
            Process_List(List, size, Cyan);
            print_OList(List, size);
            print_O(List[j], size);
    }
    return 0;
}

    
void Intro()
 {
    
    string letter, Option;
    do {
    cout << "'O' -- Open an existing student’s file." << endl;
    cout << "'A' -- Add new person to the current list." << endl;
    cout << "'R' -- Remove a person from the current list." << endl;
    cout << "'P' -- Print one student’s info in the current list." <<endl;
    cout << "'E' -- Edit information for 1 person." << endl;
    cout << "'S' -- Search." <<endl;
    cout << "'T' -- Sort the list" <<endl;
    cout << "'X' -- Exit the program." <<endl;
    cout << "Please choose an action or enter Z to exit the program: " << endl;
    cin >> letter;
    }while( Option != "z" || Option != "Z");
    
}




int read_O(Students List[], int safe, int size)
{
    int        i = 0;
    ifstream    Fin ;
    string    name ;
    
    cout <<"Enter input file name: ";
    getline(cin, name);
    Fin.open(name.c_str());
    if(Fin.fail())
        cout << "Bad file.\n" ;
    else
    { 
        while (!Fin.eof())
          {
             i++;
            if(i < SIZE)
                Read_Stu(List[i], Fin, size);
            else 
            {
                cout <<"Array is full.\n\n";
                break;
            }
    
        }
    }
    return i ;
}

void Read_Stu(Students &Temp, ifstream &Fin, int size)
{
    getline(Fin, Temp.name) ;
    Fin >> Temp.ID >> Temp.Grade ;
    Fin >> Temp.Units;
    assign_grade(Temp, size);
    Fin.ignore(10,'\n');
    
}

void print_OList(Students List[], int size)
{
    int j = 0;

    cout << "\t" << endl;
    cout << "Name" << setw(23) << "ID#" << setw(15) << "Units" << setw(15) << "GPA" << endl;
    cout << "==========================================================" << endl;
}
    
void print_O(Students Temp, int size)
{
    for (int j = 0 ; j < size ; j++)
    {
        cout << fixed << left << setw(23) << Temp.name << " " << setw(13) << Temp.ID << " " << setw(13) << setprecision(0) << Temp.Total_Units << " " << setprecision(2) << Temp.GPA << endl;
    }
    cout << "\t" << endl;
    cout << "==========================================================" << endl;
    cout << "Group of 6 Student's Totals " << Temp.Mega_Units << Temp.Avg_GPA << endl;
 }

void Process_List(Students List[], int size, float Cyan)
    {
        for (int i = 0 ; i < size; i++)
        Calc_GPA(List[i]);
    }


    
void Calc_GPA(Students &Temp) 
{ 
              int i = 0;

              Temp.Total_Units[i] += Temp.Units[i];
              Temp.Cyan[i] += (Temp.GradeK[i] * Temp.Units[i]);
              if (Temp.Total_Units[i] < 0)
               {   
                   Temp.GPA = 0;
               }
               else if (Temp.Total_Units > 0)
               {  
                   Temp.GPA = (Temp.Cyan)/Temp.Total_Units;
                   Temp.Mega_Units += Temp.Total_Units;
                   Temp.Mega_Cyan += (Temp.GPA * Temp.Total_Units);
                   Temp.Total_Units = 0;
                   Temp.Cyan = 0;
              }
}  


float assign_grade(Students &Temp, int size)
{    
    
                for(int i = 0 ; i < size ; i++) 
                {
                    while (Temp[i].Grade != "*")
                {
                 if (Temp.Grade == "A" || Temp.Grade == "a")
                    Temp[i].GradeK = 4;
                else if (Temp.Grade == "B" || Temp.Grade == "b")
                    Temp.GradeK = 3;
                else if (Temp.Grade == "C" || Temp.Grade == "c")
                    Temp.GradeK = 2;
                else if (Temp.Grade == "D" || Temp.Grade == "d")
                    Temp.GradeK = 1;
                else if (Temp.Grade == "F" || Temp.Grade == "f")
                    Temp.GradeK = 0;
            
                if (!(Temp.Grade == "A" || Temp.Grade == "a" || Temp.Grade == "B" || Temp.Grade == "b" || Temp.Grade == "C" || Temp.Grade == "c" || Temp.Grade == "D" || Temp.Grade == "d" || Temp.Grade == "F" || Temp.Grade == "f"))
                   { 
                     Temp.GradeK = 0;
                     Temp.Units = 0;
                    }
               else if (Temp.Units < 0 || Temp.Units > 5)
               {  
                   Temp.Units = 0;
               }
               
                }
                }
}       



//'O' (END)//