C#, incorrect value given after removing item from list

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C#3.5

dictionary

/*
The entire program works correctly except for the last function: removeStudent.
When I remove a student from a particular course, there is no issue - until I want to print out a listing of student currently enrolled in the course that the student was removed from. I *think* the issue is the variable numberofStudents is getting the wrong value. I have no idea why this is happening. The reason I am only storing the student ID in each course, not the entire student object is because names of students can be modified and it doesn't make sense to duplicate the data and be required to update it twice.
Issue is: Adding student, Adding course, removing student, printing students in class that the student was previously enrolled in.
Below is my code. Only three classes. Nothing wrong with Student or Main.
*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApp1
{
public class Course
{
public string courseName { get; set; }
public string teacherFirst { get; set; }
public string teacherLast { get; set; }
// used as the primary key for the course.
public static int courseCount = 0;
// used to store each course.
public static Dictionary<int, Course> courses = new Dictionary<int, Course>();
// used to store the id of each student in a course.
List
<int>
studentsInCourse = new List
<int>
();
// constructor for creating the course object.
public Course(string name, string first, string last, List
<int>
newStudentList)
{
courseName = name;
teacherFirst = first;
teacherLast = last;
studentsInCourse = newStudentList;
}
// method that creates the course.
public static void addCourse()
{
courseCount++;
Console.Write("\nPlease enter the name of the course: "); // grabbing input from user.
string name = Console.ReadLine();
Console.Write("Please enter the teacher's first name: "); // grabbing input from user.
string first = Console.ReadLine();
Console.Write("Please enter the teacher's last name: "); // grabbing input from user.
string last = Console.ReadLine();
List
<int>
studentsInCourse = new List
<int>
();
Course added = new Course(name, first, last, studentsInCourse);
courses.Add(courseCount, added);
}
// prints a listing of all courses currently available.
public static void printCourse()
{
foreach (KeyValuePair<int, Course> pair in courses)
{
Console.WriteLine("\nCourse ID: {0}", pair.Key);
Console.WriteLine("Course Name: {0}", pair.Value.courseName);
Console.WriteLine("Teacher's Name: {0} {1}", pair.Value.teacherFirst, pair.Value.teacherLast);
}
}
// adding student to a specific course.
public static void addStudentToCourse()
{
Console.Write("Please enter the student's ID: ");
string studentInput = Console.ReadLine();
int studentID = Convert.ToInt32(studentInput);
Console.Write("Please enter the course ID: ");
string courseInput = Console.ReadLine();
int courseID = Convert.ToInt32(courseInput);
courses[courseID].studentsInCourse.Add(studentID);
}
// print all students assigned to a particular course.
public static void printStudentsInCourse()
{
Console.Write("Please enter the course ID: ");
string courseInput = Console.ReadLine();
int courseID = Convert.ToInt32(courseInput);
int numberofStudents = courses[courseID].studentsInCourse.Count();
Console.WriteLine("\nCourse ID: {0}", courses[courseID].courseName);
Console.WriteLine("\nThe number of students currently enrolled in this course are: {0}\n", numberofStudents);
for (int i = 0; i < numberofStudents; i++)
{
string x = courses[courseID].studentsInCourse[i].ToString();
int addID = Convert.ToInt32(x);
Console.WriteLine("Student ID: {0} \nFull Name: {1} {2}\n", x, Student.current[addID].FirstName, Student.current[addID].LastName);
}
}
public static void removeStudent(int studentID)
{
// grabbing number of courses currently populated.
int numberofCourses = courses.Count;
// going through each course removing student if necessary.
for (int i = 1; i < numberofCourses; i++)
{
// grabbing number of students in specific course.
int numberofStudents = courses[i].studentsInCourse.Count();
// iterating through looking for student id to remove.
for (int z = 0; z < numberofStudents; z++)
{
if(courses[i].studentsInCourse[z] == studentID)
{
courses.Remove(courses[i].studentsInCourse[z]);
}
}
}
}
}
}
using System;
using System.Collections.Generic;
using System.Text;
namespace ConsoleApp1
{
public class Student
{
public string FirstName { get; set; }
public string LastName { get; set; }
// used as the primary key for the student.
public static int student_ID = 0;
public Student(string first, string last)
{
FirstName = first;
LastName = last;
}
public static Dictionary<int, Student> current = new Dictionary<int, Student>
();
// used to print all students in the system.
public static void printStudents()
{
if (current.Count == 0)
{
Console.WriteLine("There are currently no students that have been
added to the service.");
}
else
{
foreach (KeyValuePair<int, Student> pair in current)
{
Console.WriteLine("\nStudent ID: {0}", pair.Key);
Console.WriteLine("First Name: {0}", pair.Value.FirstName);
Console.WriteLine("Last Name: {0}", pair.Value.LastName);
}
}
}
// used to see if a student exist with the student id entered from user.
public static bool findStudentID(int studentID)
{
bool value = false;
if (current.ContainsKey(studentID))
{
Console.WriteLine("\nA student was found with that ID Number.\n");
value = true;
}
else
{
Console.WriteLine("\nA student was *not* found with that ID Number.");
Console.WriteLine("No edits will be made.");
}
return value;
}
// used to edit first name of a particular student.
public static void editFirstName(int studentID, string newFirstName)
{
foreach (KeyValuePair<int, Student> pair in current)
{
if (pair.Key == studentID)
{
pair.Value.FirstName = newFirstName;
}
}
}
// used to edit the last name of a particular student.
public static void editLastName(int studentID, string newLastName)
{
foreach (KeyValuePair<int, Student> pair in current)
{
if (pair.Key == studentID)
{
pair.Value.LastName = newLastName;
}
}
}
// remove student from the student dictionary.
public static void removeStudent(int studentID)
{
current.Remove(studentID);
}
}
}
using System;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
string input = null;
while (input != "10")
{
printMenu();
input = Console.ReadLine();
switch (input)
{
// add a new student.
case "1":
{
addStudent();
break;
}
// print out all student's names.
case "2":
{
Student.printStudents();
break;
}
// Edit student's first name.
case "3":
{
Console.Write("Please enter the student ID: ");
string userInput = Console.ReadLine();
int studentID = Convert.ToInt32(userInput);
bool value = Student.findStudentID(studentID);
if (value == true)
{
Console.Write("Please enter the new first Name: ");
string newFirstName = Console.ReadLine();
Student.editFirstName(studentID, newFirstName);
}
break;
}
// Edit student's last name.
case "4":
{
Console.Write("Please enter the student ID: ");
string userInput = Console.ReadLine();
int studentID = Convert.ToInt32(userInput);
bool value = Student.findStudentID(studentID);
if (value == true)
{
Console.Write("Please enter the new last Name: ");
string newLastName = Console.ReadLine();
Student.editLastName(studentID, newLastName);
}
break;
}
// remove student from list and all courses the student is
assigned to.
case "5":
{
Console.Write("Please enter the student ID: ");
string userInput = Console.ReadLine();
int studentID = Convert.ToInt32(userInput);
Student.removeStudent(studentID);
Course.removeStudent(studentID);
break;
}
// add course.
case "6":
{
Course.addCourse();
break;
}
// listing of all current courses available.
case "7":
{
Course.printCourse();
break;
}
// add student to a course.
case "8":
{
Course.addStudentToCourse();
break;
}
// print all students in a particular course.
case "9":
{
Course.printStudentsInCourse();
break;
}
// exit the program.
case "10":
{
Console.WriteLine("Closing program.");
Console.ReadKey();
break;
}
// an input was entered that was not valid to the menu.
default:
{
Console.WriteLine("*The input entered was not valid.*");
//printMenu();
break;
}
}
}
}
// a listing of all options available in the program.
public static void printMenu()
{
Console.WriteLine("\nMenu");
Console.WriteLine("To add a student enter 1.");
Console.WriteLine("To receive listing of all students enter 2.");
Console.WriteLine("Edit a student's first name enter 3.");
Console.WriteLine("Edit a student's last name enter 4.");
Console.WriteLine("To remove a student enter 5.");
Console.WriteLine("To add a course enter 6.");
Console.WriteLine("To get a listing of all current courses enter
7.");
Console.WriteLine("To add a student to a course enter 8.");
Console.WriteLine("To get a listing of all students in a course enter
9.");
Console.WriteLine("To quit the program enter 10.\n");
Console.Write("Please enter selection: ");
}
public static void addStudent()
{
Student.student_ID++;
Console.Write("\nPlease enter student's first name: "); // grabbing
input from user.
string firstName = Console.ReadLine();
Console.Write("Please enter student's last name: "); // grabbing
input from user.
string lastName = Console.ReadLine();
Student added = new Student(firstName, lastName);
Student.current.Add(Student.student_ID, added);
}
}
}

What I have tried:

I've tried finding out why the variable numberofStudents is giving the wrong value for a particular class, after a student has been removed but no luck.

I offered a free coffee to whoever helped me yesterday.
However Gerry Schmitz did not want to take me up on the offer.
10 dollar starbucks gift card for whoever helps me today.
I'm not here for handouts.