question about ifstreams

I was wondering if someone could tell me how I could do this:
I had to write this program for an exam last week and I was never clear how to do this, so I know I missed this question but I still need to know how it is done for future reference.
The idea is that I have a file named "TheGrades.txt"
So in this file, there are names with grade IDs and then grades written like this:

Maria Final 82 Midterm 65 Quiz 98 STOP -1
Tom Final 90 Midterm 84 Quiz 46 STOP -1
John Final 54 Midterm 54 Quiz 87 STOP -1
I have created have 3 classes in the program.
The idea is to use ifstream to input each line and when it gets to STOP -1, that is the end of the grades for that particular student.
I don't need to know how to write the program, I just want to know how I can input several things of different data types (strings and doubles) through ifstream because I feel like I have missed something in class pertaining to this.
After this we are supposed to output each student and the grades they recieved. I know I haven't written any functions in the program, but I just want to know how to use the ifstream (or maybe I use istream& as a parameter placeholder??) anyway, any advice would be great! Thank you!

I will try to demonstrate

Code:

---

#include <fstream>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

class Grade
{
      public:
           
      private:
              string ID;
              double score;
             
};

class Student
{
      public:
           
      private:
              string mName;
              vector <Grade> theGrades;
             
};

class Seminar
{
      public:
           
      private:
              vector <Student> theStudents;
                           
             
};

int main()
{
   
    return 0;
}

---

1. Suppose you are given an istream that has "Final 82". Write a function to read from the istream into a Grade object.

2. Suppose you are given an istream that has "Maria Final 82 Midterm 65 Quiz 98 STOP -1". Using the function you wrote in #1, write a function to read from the istream into a Student object.

3. Suppose you are given an istream that has the same input that you provided. Using the function you wrote in #2, write a function to read from the istream into a Seminar object.

4. Write the code to get the filename, open the file, use the function you wrote in #3, close the file, and you're done with input.

but I don't understand how to read two different objects from a file...??
I don't understand how I would even read Final 82 ...?

I needed some C++ practice (I've been stuck in strictly-C world for far too long) so I did this program as a quick exercise. There are a number of ways to get the data in, but this is one way.

Code:

---

bool Seminar::loadData(const string &filename)
{
    ifstream s;
    s.open(filename.c_str(), ios::in);
    if (!s.is_open())
    {
        cerr << "Unable to open " << filename << endl;
        return false;
    }
   
    while (!s.eof())
    {
        // First, get the student's name into a string.
        string name;
        s >> name;
        if (name == "")
            continue; //blank line...skip it

        // OK, create the student.
        Student st(name);

        while (true)
        {
            // Read the grades until you find the sentinel values.
            string classname;
            double grade;
            s >> classname >> grade;
            if (classname == STOP_SIGNAL && grade == STOP_GRADE)
                break; // Found the sentinels, so get out.

            // Create a grade
            Grade g(classname, grade);

            // Add the grade to the student's record
            st.addGrade(g);
        }

        // Add the student to the seminar's class list.
        theStudents.push_back(st);
    }
   
    // Close the open file.
    s.close();
    return true;
}

---

Quote:

---

I don't understand how I would even read Final 82 ...?

---

That's the easy part :) , and is given by rags_to_riches' example as:

Code:

---

s >> classname >> grade;

---

However, note that eof() should not be used to control a loop. The reason is the same as Why it's bad to use feof() to control a loop.

Right, Laserlight. It really should be (I should've known better)

Code:

---

bool Seminar::loadData(const string &filename)
{
    ifstream s;
    s.open(filename.c_str(), ios::in);
    if (!s.is_open())
    {
        cerr << "Unable to open " << filename << endl;
        return false;
    }
   
    string name;
    while (s >> name)
    {
        if (name == "")
            continue;
           
        Student st(name);
        while (true)
        {
            string classname;
            double grade;
            s >> classname >> grade;
            if (classname == STOP_SIGNAL && grade == STOP_GRADE)
                break;
            Grade g(classname, grade);
            st.addGrade(g);
        }
        theStudents.push_back(st);
    }
   
    s.close();
    return true;
}

---

Thanks guys! That was what I needed!