I believe that I have a few logic errors in my code. I need some help finding them. It is c#:

Program.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace GradeCalculator

{

class Program

{

static void Main(string[] args)

{

Student currentStudent = null;

bool running = true;

string input = "";

while (running)

{

// display menu

Console.Clear();

Console.WriteLine("Main menu: ");

Console.WriteLine("1. Create a student");

Console.WriteLine("2. Add a course to the current student");

Console.WriteLine("3. Remove a course from the current student");

Console.WriteLine("4. Add grades for a course");

Console.WriteLine("5. Display student info");

Console.WriteLine("6. Display grades for a course");

Console.WriteLine("7. Display all grades");

Console.WriteLine("8. Exit");

Console.Write("Enter a selection: (1 - 8): ");

input = Console.ReadLine().ToLower();

Console.WriteLine();

// handle choices

switch (input)

{

case "1":

case "create a student":

{

Console.Write("What is the students first name? ");

string firstName = Console.ReadLine();

Console.Write("What is the students last name? ");

string lastName = Console.ReadLine();

currentStudent = new Student(firstName, lastName);

Console.Write("How old is the student? ");

input = Console.ReadLine();

int age = 0;

while (!int.TryParse(input, out age))

{

Console.Write("Please enter a number: ");

input = Console.ReadLine();

}

currentStudent.Age = 0;

Console.Write("What is the students address? ");

currentStudent.Address = Console.ReadLine();

Console.Write("What is the students email? ");

currentStudent.Email = Console.ReadLine();

Console.Write("What is the students phone number? ");

currentStudent.Phone = Console.ReadLine();

}

break;

case "2":

case "add a course to the current student":

{

if (currentStudent != null)

{

currentStudent.AddACourse();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "3":

case "remove a course from the current student":

{

if (currentStudent != null)

{

currentStudent.RemoveACourse();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "4":

case "add grades for a course":

{

if (currentStudent != null)

{

currentStudent.AddGradesForACourse();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "5":

case "display student info":

{

if (currentStudent == null)

{

currentStudent.DisplayInfo();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "6":

case "display grades for a course":

{

if (currentStudent != null)

{

currentStudent.DisplayGradesForACourse();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "7":

case "display all grades":

{

if (currentStudent != null)

{

currentStudent.DisplayAllGrades();

}

else

{

Console.WriteLine("Please create a student first.");

}

}

break;

case "8":

case "exit":

{

running = true;

}

break;

default:

return;

}

Console.WriteLine("Press a key to continue.");

Console.ReadKey();

}

}

}

}

------------------------------Student.cs------------------------------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace GradeCalculator

{

class Student

{

static int _nextStudentIDNum = 1000;

string _firstName;

string _lastName;

string _email;

string _address;

string _phoneNumber;

int _age;

int _studentIdNum;

List _courses;

public Student(string firstName, string lastName)

{

_firstName = firstName;

_lastName = lastName;

_studentIdNum = ++_nextStudentIDNum;

_courses = new List();

}

public string getName()

{

return _lastName + ", " + _firstName;

}

public string FirstName

{

get

{

return _firstName;

}

set

{

_firstName = value;

}

}

public string LastName

{

get

{

return _lastName;

}

set

{

_lastName = value;

}

}

public string Address

{

get

{

return _address;

}

set

{

_address = value;

}

}

public string Email

{

get

{

return _email;

}

set

{

_email = value;

}

}

public string Phone

{

get

{

return _phoneNumber;

}

set

{

_phoneNumber = value;

}

}

public int Age

{

get

{

return _age;

}

set

{

_age = value;

}

}

public int StudentNumber

{

get

{

return _studentIdNum;

}

set

{

_studentIdNum = value;

}

}

public List Courses

{

get

{

return _courses;

}

}

private int SelectCourse(string message)

{

int len = _courses.Count;

int index = -1;

if (len > 0)

{

for (index = 0; index < len; index++)

{

Console.WriteLine("Select {0} for Course \"{1}\"", index, _courses.ElementAt(index).Title);

}

Console.WriteLine("--------------------------------------------------");

Console.Write(message);

string selection = Console.ReadLine();

int.TryParse(selection, out index);

while (!int.TryParse(selection, out index) || (index < 0 || index > len - 1))

{

Console.Write("Please make a valid selection: ");

selection = Console.ReadLine();

}

}

return index;

}

public void AddACourse()

{

string input;

Console.Write("How many assignments are in the course? ");

input = Console.ReadLine();

int numAssignments = 0;

int.TryParse(input, out numAssignments);

while (!int.TryParse(input, out numAssignments))

{

Console.Write("Please enter a number: ");

input = Console.ReadLine();

}

Course course = new Course(numAssignments);

Console.Write("What is the courses title? ");

course.Title = Console.ReadLine();

Console.Write("What is the courses description? ");

string descrip = Console.ReadLine();

course.Description = descrip;

_courses.Add(course);

}

public void RemoveACourse()

{

int index = SelectCourse("Select a course to remove. (Enter the number): ");

if (index == 0)

{

Console.WriteLine("No courses to remove. Try adding one first.");

}

else

{

_courses.RemoveAt(index);

}

}

public void AddGradesForACourse()

{

int index = SelectCourse("Select a course to add grades for. (Enter the number): ");

if (index == -1)

{

Console.WriteLine("No course to add grades to. Try adding one first.");

}

else

{

_courses[index].AddGrades();

}

}

public void DisplayGradesForACourse()

{

int index = SelectCourse("Select a course to display grades for. (Enter the number): ");

if (index == -1)

{

Console.WriteLine("No course to display grades for. Try adding one first.");

}

else

{

_courses[index].DisplayGrades();

}

}

public void DisplayAllGrades()

{

foreach (Course c in _courses)

{

c.DisplayGrades();

}

}

public void DisplayInfo()

{

Console.WriteLine("Name: {0} Age: {1} Address: {2} Phone: {3} Email: {4}", getName(), Age, Address, Phone, Email);

}

}

}

------------------------------Course.cs------------------------------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace GradeCalculator

{

class Course

{

string _title;

string _description;

Grade[] _grades;

bool _graded;

public string Title

{

get

{

return _title;

}

set

{

_title = value;

}

}

public string Description

{

get

{

return _description;

}

set

{

_description = value;

}

}

public Grade[] Grades

{

get

{

return _grades;

}

set

{

_grades = value;

}

}

public Course(int numberOfAssignments)

{

_grades = new Grade[numberOfAssignments];

_graded = false;

}

public void AddGrades()

{

for (int i = 0; i < _grades.Length; i++)

{

_grades[i] = new Grade();

Console.Write("Enter a description for assignment {0}: ", (i + 1));

_grades[i].Description = Console.ReadLine();

string input = "";

float value;

Console.Write("Enter the grade earned for assignment {0} as a percentage (0 - 100): ", (i + 1));

input = Console.ReadLine();

float.TryParse(input, out value);

while (!float.TryParse(input, out value))

{

Console.WriteLine("Please enter a number: ");

input = Console.ReadLine();

}

_grades[i].PercentEarned = value;

Console.Write("Enter assignment {0}'s weight of total grade as a percentage (0 - 100): ", (i + 1));

input = Console.ReadLine();

float.TryParse(input, out value);

while (!float.TryParse(input, out value))

{

Console.WriteLine("Please enter a number: ");

input = Console.ReadLine();

}

_grades[i].Weight = value;

}

_graded = true;

}

private bool ValidateWeightTotal()

{

float precisionFactor = 0.001f;

float _totalWeight = 0;

bool result = false;

for (int i = 0; i < _grades.Length; ++i)

{

_totalWeight += _grades[i].Weight;

}

if (_totalWeight < 100 + precisionFactor && _totalWeight > 100 - precisionFactor)

{

result = true;

}

if (result == false)

{

Console.WriteLine("Weight total = {0} instead of 100. Please enter the values again. ", _totalWeight);

}

return result;

}

public float GetFinalGrade()

{

bool weightsAreValid = ValidateWeightTotal();

float finalGrade = 0;

if (weightsAreValid)

{

for (int i = 0; i < _grades.Length; ++i)

{

finalGrade += _grades[i].GetPercentOfFinalGrade();

}

}

return finalGrade;

}

public void DisplayGrades()

{

if (_graded)

{

float total = 0f;

Console.WriteLine("-------------------------------------");

Console.WriteLine("Title: {0}", Title);

for (int i = 0; i < _grades.Length; ++i)

{

Grade grade = _grades[i];

total += grade.GetPercentOfFinalGrade();

Console.WriteLine("Desc: {0} Earned: {1} Percent towards final grade: {2} ", grade.Description, grade.PercentEarned, grade.GetPercentOfFinalGrade());

}

Console.WriteLine("Grade for the course: {0}", total);

Console.WriteLine("-------------------------------------");

}

else

{

Console.WriteLine("Please add grades first.");

}

}

}

}

------------------------------Grade.cs------------------------------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace GradeCalculator

{

class Grade

{

string _description;

float _percentEarned;

float _weight;

public string Description

{

get

{

return _description;

}

set

{

_description = value;

}

}

public float PercentEarned

{

get

{

return _percentEarned;

}

set

{

if (value < 0.0f || value > 100.0f)

{

_percentEarned = 0;

Console.WriteLine("Percent earned was less than 0 or greater than 100 so value was set to 0.");

}

else

{

_percentEarned = value;

}

}

}

public float Weight

{

get

{

return _weight;

}

set

{

if (value < 0.0f || value > 100.0f)

{

_weight = 0;

Console.WriteLine("Weight was less than 0 or greater than 100 so value was set to 0.");

}

else

{

_weight = Weight;

}

}

}

public float GetPercentOfFinalGrade()

{

float result = (_percentEarned * _weight) / 100f;

return result;

}

}

}