How does one correctly pass on ofstream object? - c++

Question

I am writing code to have input student and grade objects, sort them, calculate an average gpa, and output them to a file. My current problem is that the output of my student objects are given after I sort them and print them, but the code does not seem to leave the loop once I do that. I have a print function in which I am passing an ofstream. From debugging, I know that the out ofstream object reads everything, but then it seems to freeze, and not output anything else into it. Can somebody tell me if I passed by reference incorrectly, or if I need to do something else? The error where the compiler didn't keep going through is marked in the code.
Sorry, so for more information, below is a snip it of what is run
output code in text file
Notice how "got through it" is only displayed once. I know that it's not an issue opening the file and outputting, because it actually did output the right stuff. Also, for correction, the compiler actually compiles everything fine. It is at runtime where the terminal stalls and nothing more is output.
#include <vector>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <fstream>
#include <string>
#include "Grade.h"
#include "Student.h"
using namespace std;
const double A_NUM = 4.0, B_NUM = 3.0, C_NUM = 2.0, D_NUM = 1.0, E_NUM = 0.0, B_PLUSSNUM = 3.4, C_PLUSSNUM = 2.4, D_PLUSSNUM = 1.4;
const double A_MINUSNUM = 3.7, B_MINUSNUM = 2.7, C_MINUSNUM = 1.7, D_MINUSNUM = 0.7;
const int FIRST_INDEX= 0;
const int START_NUM = 0;
const int LESS_ONE = 1, ABOVE_ONE = 1;
const int START_GRADE = 0;
void calcgrades(vector<Grade>& grades)//function that calculates gpa based on letter grades
{
const string A = "A", A_MINUS = "A-", B_PLUSS = "B+", B = "B", B_MINUS = "B-", C_PLUSS = "C+", C = "C", C_MINUS = "C-", D_PLUSS = "D+", D = "D", D_MINUS = "D-", E = "E";
int counter = START_NUM;//used to keep track of current student and current total grade
double current_grade = START_NUM;
for(int i = 0; i < grades.size();i++)
{
//while loop to get the student's current total grade if the next student id is different than the first one.
while(i < grades.size()-LESS_ONE && grades[i].getid() == grades[i+ABOVE_ONE].getid())
{
if (grades[i].getgrade() == A)
{
current_grade == A_NUM + current_grade;
}
if (grades[i].getgrade() == B)
{
current_grade == B_NUM + current_grade;
}
if (grades[i].getgrade() == C)
{
current_grade == C_NUM + current_grade;
}
if (grades[i].getgrade() == D)
{
current_grade == D_NUM + current_grade;
}
if (grades[i].getgrade() == E)
{
current_grade == E_NUM + current_grade;
}
if (grades[i].getgrade() == B_PLUSS)
{
current_grade == B_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == C_PLUSS)
{
current_grade == C_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == D_PLUSS)
{
current_grade == D_PLUSSNUM + current_grade;
}
if (grades[i].getgrade() == A_MINUS)
{
current_grade == A_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == B_MINUS)
{
current_grade = B_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == C_MINUS)
{
current_grade = C_MINUSNUM + current_grade;
}
if (grades[i].getgrade() == D_MINUS)
{
current_grade = D_MINUSNUM + current_grade;
}
}
if (grades[i+ABOVE_ONE].getid() != grades[i].getid() || i == grades.size()-LESS_ONE)
{
//computes the average if the currentid is not equal to the nextid
double avggpa = current_grade/counter;
grades[i].newgpa(avggpa);
counter = START_NUM;//resets counter for a new student to get his gpa
}
counter++;
}
}
int main(int argc, char* argv[])
{
string student_file, grades_file, idnum, name, address, pnum, course, gletter;
//creates student and grade objects from respective classes
vector<Student> students;
vector<Grade> grades;
student_file = argv[1];
//reads in information from file to import into student objects
ifstream sfile;
sfile.open(student_file);
while(getline(sfile, idnum))//gets the student information from student file
{
getline(sfile, name);
getline(sfile, address);
getline(sfile, pnum);
//creates student objects to import info. into, and inserts into students vector
Student s(idnum, name, address, pnum);
students.push_back(s);
}
sfile.close();
//opens information from the grade file
grades_file = argv[2];
//reads from file to import into grades objects
ifstream gfile;
gfile.open(grades_file);
//gets the grade information from the grades file
while(getline(gfile, course))
{
getline(gfile, idnum);
getline(gfile, gletter);
//creates grade objects to import info, and inserts into grades vector
Grade g(course, idnum, gletter, START_GRADE);
grades.push_back(g);
}
gfile.close();
//reads the query file
string query_file;
query_file = argv[3];
ifstream qfile;
qfile.open(query_file);
//reads from query file
//creates vector to store each student number
vector<string> query_nums;
string incheck;
while(getline(qfile, incheck))
{
query_nums.push_back(incheck);
}
qfile.close();
//sorts the information for the students
sort(students.begin(), students.end());
//sorts the information for the grades
sort(grades.begin(), grades.end());
ofstream outtxt;
string out_file = argv[4];
outtxt.open(out_file);
//outputs the student information, sorted now.
for(int i = 0; i < students.size();i++)
{
students[i].print(outtxt);
outtxt << "got through it";
}
//compiler did not get past here!
outtxt << "We're here!";
//outputs the grades with student id's, now sorted
for (int i = 0; i < grades.size(); i++)
{
grades[i].print(outtxt);
outtxt << "\n\n" << "some output!";
}
//calculates the average gpa for every student
calcgrades(grades);
for(int i = 0; i < query_nums.size(); i++)//goes through each query number to check first
{
for (int j = 0; j < students.size(); j++)//after, goes through each student object
{
if (query_nums[i] == students[j].getid())
{
//finds the gpa in the grades class that matches the student id
for (int k = 0; k < grades.size(); k++)
{
if (grades[k].getid() == query_nums[i])//
{
//outputs the resulting id, avg gpa, and name of matching students
outtxt << grades[i].getid() << "\tthere is nothinghere" << grades[i].getgpa() << "\t" << students[i].getname();
}
}
}
}
}
outtxt.close();
return 0;
}
student class with print function
class Student
{
private:
string idnum;
string name;
string address;
string pnum;
public:
//defines constructor
Student(string idnum,string name,string address,string pnum);
//prints each student info
void print(ofstream& out);
string getname();
string getid();
bool operator < (Student s) const {
return idnum < s.idnum;
}
};
student cpp file
#include "Student.h"
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;
//Student constructor, used to make student objects
Student::Student(string id,string nm,string add,string pnumber)
{
idnum = id;
name = nm;
address = add;
pnum = pnumber;
}
void Student::print(ofstream& out)
{
out << name << endl << idnum << endl << pnum << endl << address << endl;
}
string Student::getname()
{
//returns the student name
return name;
}
string Student::getid()
{
return idnum;
}

Answer 1

In answer your question regarding how to correctly pass an ofstream object, you are passing it correctly.
So why doesn't it work? From what is available to observe from your code, it should work just fine. I would suggest debugging the output file name in these lines of code:
ofstream outtxt;
string out_file = argv[4];
outtxt.open(out_file);
Verify that the open function succeeded by checking the ios::fail flag after calling the open function.
Try something like this after opening:
if (ios::fail)
cout << "fail";
I hope this helps.
Edited: There may be other problems, but the calcgrades() function has an access violation on the last for loop iteration, after the while loop, at this if statement:
if (grades[i+ABOVE_ONE].getid() != grades[i].getid() || i == grades.size()-LESS_ONE)