Reading numbers from text and outputting average - c++

Question

So I am working to read text from a file (line by line) and output the ID, average of 4 grades following the ID, and the letter grade. So the letter grade for any average grade of 50 or above is S, anything below 50 is a U, and 2 excused classes results in the letter grade I. (No S or U if more than or equal to 2 excused).
So lets say file has the numbers:
42 50 51 57 52
48 90 -1 60 -1
40 46 -1 59 45
47 50 -1 49 50
The output should look something like this:
ID=42 Avg=52.5 Grade=S
ID=48 Excused=2 Grade=I
ID=40 Avg=50.0 Grade=S
ID=47 Avg=49.7 Grade=U
Number of Grades of Type
S U I
2 1 1
This is the output I am receiving from my code
It is reading all the numbers, but i need it to read the first number as ID and following 4 numbers as grade.
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
ifstream in;
ofstream results;
string filename;
char grade;
int S = 0, U = 0, I = 0, i = 0, ID, excused = 0, avg;
double allscores = 0;
cout << "Enter the name of the file that has the scores of students: " << endl;
cin >> filename;
cout << "Enter the number of scores for each student: " << endl;
cin >> ID;
in.open(filename);
results.open("results.txt");
if (in)
{
while (in >> ID)
{
int first = 0
for (i = 0; i<=4; i++)
{
if (first == -1)
excused++;
else
allscores += first;
}
if (first > 4)
{
avg = allscores / (4 - excused);
if (avg >= 50.0)
{
grade = 'S';
S++;
cout << "ID=" << ID << " Avg=" << avg << " Grade =" << grade << endl;
}
else
{
grade = 'U';
U++;
cout << "ID=" << ID << " Avg=" << avg << " Grade =" << grade << endl;
}
}
else
{
grade = 'I';
I++;
cout << "ID=" << ID << " Excused=" << excused << " Grade =" << grade << endl;
}
}
}
else
{
cout << "Couldn't open file\n";
}
cout << "Number of Grades of Type" << endl;
cout << "S " << "U " << "I" << endl;
cout << S << " " << U << " " << I << endl;
in.close();
results.close();
system("pause");
return 0;
}

Answer 1

Your variable int first=0 is not being assigned any value other than 0 in your code so the statement if(first>4) will always be false and result the output your are getting.
You can do something like this:
while (in >> ID)//this is supposed to get the ID of each student, in order for that to happen you need to read all the 4 scores inside this loop before coming here and reading the next ID,otherwise everything will read as an ID
{
int first = 0
excused=0;//you need to reset excused on every iteration
allscores=0;//you need to reset allscore on every iteration
for (i = 0; i<4; i++)
{//here you need to get all the 4 scores
in>>first;//get each score in first
if (first == -1)
excused++;
else
allscores += first;
}
if(excused<2)//instead of if(first>4)
...//do your calculation for average score
else
...//set the grade to 'I'...
}

Answer 2

Here is my final solution:
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main()
{
ifstream in;
ofstream results;
string filename;
char grade;
int S = 0, U = 0, I = 0, i = 0, ID, excused = 0, avg;
double allscores = 0;
cout << "Enter the name of the file that has the scores of students: " << endl;
cin >> filename;
cout << "Enter the number of scores for each student: " << endl;
cin >> ID;
in.open(filename);
results.open("results.txt");
if (in)
{
while (in >> ID)
{
int first = 0;
excused = 0;
allscores = 0;
for (i = 0; i < 4; i++)
{
in >> first;
if (first == -1)
excused++;
else
allscores += first;
}
if (excused < 2)
{
avg = allscores / (4 - excused);
if (avg >= 50.0)
{
grade = 'S';
S++;
results << "ID=" << ID << " Avg=" << avg << " Grade =" << grade << endl;
}
else
{
grade = 'U';
U++;
results << "ID=" << ID << " Avg=" << avg << " Grade =" << grade << endl;
}
}
else
{
grade = 'I';
I++;
results << "ID=" << ID << " Excused=" << excused << " Grade =" << grade << endl;
}
}
}
else
{
cout << "Couldn't open file\n";
}
results << "Number of Grades of Type" << endl;
results << "S " << "U " << "I" << endl;
results << S << " " << U << " " << I << endl;
in.close();
results.close();
system("pause");
return 0;
}
After the code I have it output to a file named "results".
Thanks for the help. I guess my while loop was the biggest mistake.
Especially not adding in the in >> first portion.