Validating loop input and writing to file

[CassandraB]

I have to write a program that uses files and nested loops to create a file from the quiz grades entered by the user, then read the grades from the file and calculates the average quiz grade for a class. Each student takes 4 quizzes. Use a nested loop to write each students quizzes to a file. Then read the data from the file in order to display the student's average score and the class average.

The problem I am having is validating test scores and having them write to the file. I do not want the test score to be >100. I have tried several different methods of validating but cant seem to find the correct way to do it inside the loop.

//Cassandra Hamric
//30 March 2016
//This program claculates average quiz grades for a class.

#include<iostream>
#include<fstream>
#include<iomanip>
using namespace std;
int main()
{
	
 ofstream outfile;
 outfile.open("quizgrades.txt"); // Open a file named quizgrades.txt
 int studentID,grades,choice=1;

 while(choice!=0)
 {
     cout<<"Enter the student id : "<<endl; // Get student ID
     cin>>studentID;
	 cout <<endl;

     outfile<<studentID<<" "; // Send student ID to file
     for(int id=0;id<4;id++)
     {
         cout<<"Enter quiz grades : "; //get quiz grades
         cin>>grades;
         outfile<<grades<<" "; //send grades to file

		 if (grades > 100) //Validate quiz scores are not above 100.
			 cout <<"Error! Grade must not be above 100. Please re-enter grades.";
		 cin >> grades;
		 outfile <<grades << " ";
	 }
	 
	

     outfile<<endl;
     cout<<"\nEnter 0 for no more students to enter. Enter 1 for more students."<<endl; // Choose if more students to enter
     cin>>choice;
 }
 outfile.close(); //close outfile


 ifstream infile;
 infile.open("quizgrades.txt"); // Open the file
 int count=1;
 int classTotal=0;
 while(!infile.eof())
 {
     infile>>studentID; //Read the student ID's
     int total=0;
     for(int id=0;id<4;id++)
     {
         infile>>grades; // Read the student grades
         total+=grades;
     }
    double average= total/4.0; // calculate average score
     classTotal+=total;
     cout<<"Student "<<count<<" average score is : "<<average<<endl;
     count++;
     char ch;
     infile>>ch;
 }
 count--;
 float netAverage= float(classTotal)/(count*4);
  cout.precision(4);
  cout<<"Average quiz score for the class is "<<netAverage <<endl;

  system ("pause"); 
 return 0;

}

[CS Student]

So what do you want to have happen if it is true that the grade is greater than 100? The logic looks correct. If you are wanting to re-prompt, you need to stick the cin in some sort of loop when you are re-prompting for the grade.

[CassandraB]

It doesn't work. The program will ask for like 8 grades as it is. I changed it to

	 	while (grades > 100)
		{
			cout << "\n Grade must not be over 100"<<endl; // If Start is Greater than End, Output Error
			cout <<"Enter quiz grades : " ;
			cin >> grades;
			 outfile<<grades<<" "; //send grades to file
		}

And that does not work either, it will keep the first grade of 200 and copy that to the text file. lf the grade is over 100, I want it to re-start the input of that particular students grades.

[Thomas1965]

Your logic is wrong.

outfile<<grades<<" "; //send grades to file
if (grades > 100) //Validate quiz scores are not above 100.
  cout <<"Error! Grade must not be above 100. Please re-enter grades.";

You need to check the grade before you write it to the file.

I would use a separate function to get the grade:

int GetGrade()
{
  bool valid = false;
  int grade = 0;

  while (!valid)
  {
    cout << "Enter grade (max 100): ";
    cin >> grade;
    if (grade <= 100)
      return grade;   
  }
}