good code

//including libraries
#include <iomanip>
#include <fstream>
#include <iostream>

using namespace std;

void function_inputData();

int main(){

    int num_students;

    const double GRADE_A = 90.0;
    const double GRADE_B = 80.0;
    const double GRADE_C = 70.0;
    const double GRADE_D = 60.0;

    const int STUDENT_COUNT = 3;
    const int STRING_COUNT = 9;
    const int INT_COUNT = 2;
    const int COURSE_COUNT = 3;
    const int GRADE_COUNT = 6;

    const string WARN = "Warning: Your grade is low and needs improvment";
    const string COMMENDATION = "Commendation: Congratulations, Your grade is excellent!";
    const double WARN_NUM = 70.0;
    const double COMMENDATION_NUM = 95.0;

    const string FILE_ERROR = "Error: File is not reading.";
    const string INV_NUM = "Error: invalid number, an integer must be between 1 and 100";
    const string INV_FLOAT = "Error: invalid input, floating point must be between 1.0 and 100.0";
    const string INV_STRING = "Error: string must be longer than 0 spaces";
    const string ARRAY_ERROR = "Error: Array out of bounds";

    // Get input for number of students in class
    do {
        cout << "Please input the number of students in the class " << endl;
        cin >> num_students;
        if (num_students < STUDENT_COUNT)
            cout << "Number of students must be greater than 3" << endl;
    } while (num_students < STUDENT_COUNT);



    //Declare files
    ifstream file_input;
    ofstream file_output;

    //open input file
    file_input.open("Project4_David_Janicki_Input.txt");
    if (file_input.fail()){
        cout << FILE_ERROR << endl;
        return 0;
    }

    //create student arrays
    string nonNumeric [num_students][STRING_COUNT];
    int numeric1 [num_students][INT_COUNT];
    double numeric2 [STUDENT_COUNT][COURSE_COUNT][GRADE_COUNT];
    char letterGrade[STUDENT_COUNT][COURSE_COUNT];

    // outer loop for students
    for (int i=0; i<num_students; i++){
        //check for error
        if (i < STUDENT_COUNT) {
            cout << ARRAY_ERROR << endl;
          //  break;
        }
        // getting input from file and saving in arrays
        //student name
        getline(file_input, nonNumeric[i][0]);
        if (nonNumeric[i][0].length() <= 0){
            cout << INV_STRING << endl;
            continue;
        }
        // student id
        getline(file_input, nonNumeric[i][1]);
        if (nonNumeric[i][1].length() <=0){
            cout << INV_STRING << endl;
            continue;
        }
        //student address
        getline(file_input, nonNumeric[i][2]);
        if (nonNumeric[i][2].length() <=0){
            cout << INV_STRING << endl;
            continue;
        }
        //student phone number
        getline(file_input, nonNumeric[i][3]);
        if (nonNumeric[i][3].length() <=0){
            cout << INV_STRING << endl;
            continue;
        }
        //student social
        getline(file_input, nonNumeric[i][4]);
        if (nonNumeric[i][4].length() <=0){
            cout << INV_STRING << endl;
            continue;
        }
        //student age
        file_input >> numeric1[i][0];
        file_input.ignore();
        if (numeric1[i][0] < 1 || numeric1[i][0] > 100){
            cout << INV_NUM << endl;
           // break;
        }
        // years at txstate
        file_input >> numeric1[i][1];
        file_input.ignore();
        if (numeric1[i][1] < 1 || numeric1[i][1] > 100){
            cout << INV_NUM << endl;
          //  break;
        }

        //class loop
        for (int n=0; n < COURSE_COUNT; n++){
            //check for error
            if (5+n > STRING_COUNT){
                cout << ARRAY_ERROR << endl;
                //break;
            }
            //course number
            getline(file_input, nonNumeric[i][5+n]);
            if (nonNumeric[i][5+n].length() <= 0){
                cout << INV_STRING << endl;
                continue;
            }
            numeric2[i][n][5] = 0.0;

            for (int x=0; x<5; x++){
                //check for error
                if (x > GRADE_COUNT){
                    cout << ARRAY_ERROR << endl;
                   // break;
                }

                //exam score
                file_input >> numeric2[i][n][x];
                file_input.ignore();
                if (numeric2[i][n][x] <1.0 || numeric2[i][n][x] > 100.0){
                    cout << INV_FLOAT << endl;
                  //  break;
                }

                //compute grade #
                switch (x) {
                    case 0:
                     numeric2[i][n][5] += numeric2[i][n][x] * .1;
                     break;
                    case 1:
                    case 2:
                     numeric2[i][n][5] += numeric2[i][n][x] * .15;
                     break;
                    case 3:
                     numeric2[i][n][5] += numeric2[i][n][x] * .2;
                     break;
                    case 4:
                     numeric2[i][n][5] += numeric2[i][n][x] * .4;
                     break;


            }
            }

    if (numeric2[i][n][5] >= GRADE_A){
            letterGrade[i][n] = 'A';
        }else if (numeric2[i][n][5] >= GRADE_B) {
            letterGrade[i][n] = 'B';
        }else if (numeric2[i][n][5] >= GRADE_C) {
            letterGrade[i][n] = 'C';
        }else if (numeric2[i][n][5] >= GRADE_D) {
            letterGrade[i][n] = 'C';
        } else {
         letterGrade[i][n] = 'F';}

        }
    }
    //close input file
    file_input.close();


    //open output file
    file_output.open("Project4_David_Janicki_Output.txt");

    // student loop
    for (int i=0; i<num_students; i++){
        //check for error
        if (i < STUDENT_COUNT) {
            cout << ARRAY_ERROR << endl;
           // break;
        }
        //write information to file
        file_output << "============================================================================================" << endl;
        file_output << setw(46) << "Student Grade Sheet" << endl;
        file_output << "============================================================================================" << endl;
        file_output << setw(33) << "Name of Student: \t" << nonNumeric[i][0] << endl;
        file_output << setw(33) << "Student ID: \t" << nonNumeric[i][1] << endl;
        file_output << setw(33) << "Student Address: \t" << nonNumeric[i][2] << endl;
        file_output << setw(33) << "Student Telephone Number: \t" << nonNumeric[i][3] << endl;
        file_output << setw(33) << "Student Social Security # \t" << nonNumeric[i][4] << endl;
        file_output << setw(33) << "Student Age: \t" << numeric1[i][0] << endl;
        file_output << setw(33) << "number of years at Texas State: \t" << numeric1[i][1] << endl;

        //course loop
        for (int n=0; n < COURSE_COUNT; n++){
            //check for error
            if (5+n > STRING_COUNT){
                cout << ARRAY_ERROR << endl;
             //   break;
            }
        //write course # to file
        file_output << endl << setw(33) << "Course Number \t" << nonNumeric[i][5+n] << endl;
        file_output << "--------------------------------------------------------------------------------------------" << endl;
        //exam loop
        for (int x=0; x<5; x++){
                //check for error
                if (x > GRADE_COUNT){
                    cout << ARRAY_ERROR << endl;
                //    break;
                }

                file_output << setw(33) << "Exam #" << x+1 << ": \t" << fixed << showpoint <<
                    setprecision(2) << numeric2[i][n][x] << endl;
        }
        //write grades to file
        file_output << setw(28) << "Numerical Grade in " << nonNumeric[i][5+n] <<
         ": \t" << fixed << showpoint << setprecision(2) << numeric2[i][n][5] << endl;
        file_output << setw(28) << "Letter Grade in " << nonNumeric[i][5+n] <<
         ": \t" << letterGrade[i][n] << endl;

         //write warning or commendation
         if (numeric2[i][n][5] < WARN_NUM)
            file_output << setw(37) << "Comment: \t" << WARN << endl;
         else if (numeric2[i][n][5] >= COMMENDATION_NUM)
            file_output << setw(37) << "Comment: \t" << COMMENDATION << endl;
    }
    //file_output << endl << endl;
    }
    //close file
    file_output.close();

    cout << "Data written to file" << endl;

    return 0;

}