#include<iostream>
#include<string>
#include<iomanip>
#include<fstream>
#include<cstdlib>
using namespace std;

#define outFile "output.txt"
#define inFile "studInfo.txt"

struct Grades
{
	float exams[3];
	float avg;
	string lname;
	char grade;
};

char lGrade(float avg);
void write(ofstream& out, Grades);
int read(ifstream & in, Grades studs[]);
int search(const Grades studs[], int numberUsed, string target);

int main()
{
	//Variable declaration
	Grades studs[30];//Array of structures
	float avg, total = 0.0;
	int numStuds, index;
	string target;
	ofstream out;
	ifstream in;
	
	out.open(outFile);
	if (out.fail())
	{
		cerr<<"***ERROR: Cannot open " <<outFile
			<<" for output." << endl;
		out.close();
		return EXIT_FAILURE; 
   }

   in.open(inFile);
   if (in.fail())
   {
	   cerr<<"***ERROR: Cannot open " <<inFile
		   <<" for input." << endl;
	   in.close();
	   return EXIT_FAILURE; 
   }

   //Variable initialization
   int ch;

   //Dynamic entry of the data
   numStuds = read(in, studs);
   for(int i = 0; i < numStuds; i++)
   {
	   total = 0;
		for (int j = 0; j < 3; j++)
			{
				//calculation
				total += studs[i].exams[j];
			}
		studs[i].avg=total / 3.0;
		avg = studs[i].avg;
		//letter grade: call the lGrade function
		
		studs[i].grade = lGrade(avg);
		//display the results
		write(out,studs[i]);	
   }
	out.close();
	in.close();

	//Search section
	cout<<"Please enter the student's last name: ";
	cin>>target;

	//Call the function
	index = search(studs, numStuds, target);
	if (index != -1)
		cout<<"The letter grade for "<<target<<" is "<<studs[index].grade<<endl;
	else
		cout<<"The student is not enrolled in the course."<<endl;

	for (int pass = 1; pass < 30; pass++) 
	{
		for (int i=0; i < 30-pass; i++) 
		{
			if (studs[i] > studs[i+1]) 
			{
               int temp = studs[i]; studs[i] = studs[i+1]; studs[i+1] = temp;
			}
		}
	}
	cout<<temp<<endl;
	return 0;
}
int read(ifstream &in, Grades studs[])
{
	int ch; int i = 0;

	while(ch = in.peek() != EOF)
	{
		in >> studs[i].lname;
	
		for(int a = 0; a < 3; a++)
			in >> studs[i].exams[a];
		i++;
	}
	return(i);
}
char lGrade(float avg)
{
	//Declare variable
	char grade;

	//Calculate letter grade
	if(avg >= 90)
		grade = 'A';
	else if (avg >= 80)
		grade = 'B';
	else if (avg >= 70)
		grade ='C';
	else if (avg >= 60)
		grade = 'D';
	else
		grade = 'F';
	return grade;
}

void write (ofstream& out, Grades studs)
{
	out<<setiosflags(ios::fixed)<<setprecision(2);
	out<<"Name: "<<studs.lname<<endl
		<<"Average: "<<studs.avg<<endl
		<<"Grade: "<<studs.grade<<endl<<endl;	
}
int search(const Grades studs[], int numberUsed, string target)
{
	int index = 0;
	bool found = false;
	while ((!found) && (index < numberUsed))
		if (target == studs[index].lname)
			found = true;
		else
			index++;

		if (found)
			return index;
		else 
			return -1;
}

Grades g1, g2;
// ... fill in values ...
if (g1 < g2) {
   // do something
} else {
   // do something else
}

struct Grades
{
	float exams[3];
	float avg;
	string lname;
	char grade;
};

// this is pseudo code
void bubbleSort(Array of Grades) {
   for each element in the array grades
      for each element in the array grades starting at above index
         if comparator(grade1, grade2)
            swap(grade1, grade2)
}

int comparator(Grade, Grade) {
   if Grade.avg < Grade.avg
      // do something
   //...
}