Can't pass filestream as function parameter? - c++

Question

Here is my code for an assignment I have. Whenever I try and compile I get an error for my read function due to something in "ios_base.h" I am not sure what to do and/or if my code does the intended function of taking a file and moving it's elements into a separate file that has the name and average next to each other.
#include <iostream>
#include <fstream>
#include <sstream>
#include <iomanip>
using namespace std;
struct Student
{
string fname;
string lname;
double average;
};
int read(ifstream, Student s[]);
void print(ofstream fout, Student s[], int amount);
int main()
{
const int size = 10;
ifstream fin;
ofstream fout;
string inputFile;
string outputFile;
Student s[size];
cout << "Enter input filename: ";
cin >> inputFile;
cout << "Enter output filename: ";
cin >> outputFile;
cout << endl;
fin.open(inputFile.c_str());
fout.open(outputFile.c_str());
read(fin , s);
print(fout, s, read(fin, s));
}
int read(ifstream fin, Student s[])
{
string line;
string firstName;
string lastName;
double score;
double total;
int i=0;
int totalStudents=0;
Student stu;
while(getline(fin, line)){
istringstream sin;
sin.str(line);
while(sin >> firstName >> lastName){
stu.fname = firstName;
stu.lname = lastName;
while(sin >> score){
total *= score;
i++;
}
stu.average = (total/i);
}
s[totalStudents]=stu;
totalStudents++;
}
return totalStudents;
}
void print(ofstream fout, Student s[], int amount)
{
ostringstream sout;
for(int i = 0; i<amount; i++)
{
sout << left << setw(20) << s[i].lname << ", " << s[i].fname;
fout << sout << setprecision(2) << fixed << "= " << s[i].average;
}
}

Answer 1

Stream objects are not copyable. Their copy constructor is deleted. They must be passed by reference, not by value:
int read(ifstream &, Student s[]);
void print(ofstream &fout, Student s[], int amount);
etc...

Answer 2

Sam Varshavchik's answer is correct, but he didn't mention why stream objects don't allow you to copy them.
The issue here is that a stream object owns a buffer, and buffers can't be copied safely.
To take an example, suppose you have data coming in over a network socket and a buffer sitting in front of it, and you copy this buffered reader. If you read from the copy, it will read some indeterminate amount of data and put it into the buffer. This data is now gone from the network socket and only exists in the buffer. Now suppose you read from the copy. Then you'll get some indeterminate amount of data that came after the data you read in the original. Going back and forth in this way, you'd get two "streams" with gaps in them where the other reader was reading the data.