Thread: reterning a reference to the input stream

I'm reading Accellerated C++ and they use a program for reading grades throughout the book, the code itself is a little confusing since there are a lot of what I beleive to be redundant function calls but there's one thing I don't understand. In one chapter we quantify all the functions and the student_info structure to a class, one function of which we use to read the info.

Code:

 class Student_info {
public:
	Student_info();              // construct an empty `Student_info' object
	Student_info(std::istream&); // construct one by reading a stream
	std::string name() const { return n; }
	bool valid() const { return !homework.empty(); }

	// as defined in 9.2.1/157, and changed to read into `n' instead of `name'
	std::istream& read(std::istream&);

	double grade() const;    // as defined in 9.2.1/158
private:
	std::string n;
	double midterm, final;
	std::vector<double> homework;
};

in the actual use of the program, it's used as

Code:

                vector<Student_info> students;
	Student_info record;
	string::size_type maxlen = 0;

	// read and store the data
           while (record.read(cin)) {                           // changed
		maxlen = max(maxlen, record.name().size());      // changed
		students.push_back(record);
	}

I uderstand that returns an istream because it is used in a while condition, but why a reference to an istream?

Some of the code is confusing in itself but what exactly is the benefit of returning a reference to an input stream?

you should add "DUUUUH!" at the end. I should have read that.

...that was rather anti-climactic.