Student Management System, C#

Language: Layout:

using System;
using System.Collections.Generic;

namespace Rextester
{
    
    public class Student
    {
        public string name,city;
        public int sno,totalMarks = 0;
        
        public Student(int sno, string name, string city, int totalMarks)
        {
            this.sno = sno;
            this.name = name.ToLower();
            this.city = city.ToLower();
            this.setTotalMarks(totalMarks);

}
        
        public void setTotalMarks(int totalMarks)
        {
            if(totalMarks < 0 || totalMarks > 100)
            {
                Console.Write("\n\n *Marks should be Non-negative and less than 100");
                totalMarks = 0;
            }
            
            this.totalMarks = totalMarks;
        }
            
    }    
    
    public class Program
    {
        public static List<Student> students = new List<Student>();
        static int sno, totalMarks;
        static string name,city;
        
        public static void Main(string[] args)
        {
            string ch = "";
            Console.WriteLine("\n\tSTUDENT MANAGEMENT SYSTEM");
            Console.WriteLine("----------------------------------------");

Console.WriteLine("1. New Student\n2. Update Student\n3. Delete Student\n4. View Student\n5. View All Students\n6. View Student Result\n7. Exit\n");

do{

Console.Write("\nSelect your choice : ");
                int choice = 0;
                bool IsConversionSuccessful = int.TryParse(Console.ReadLine(), out choice);
                
                if(!IsConversionSuccessful)
                   Console.Write("\nPlease enter a valid format");
                else
                {
                    switch(choice)
                    {
                        case 1:
                            enterDetails();
                            bool exists = students.Exists(x => x.sno == sno);
                            if(exists)
                                Console.Write("\n\n *Sno already exists");
                            else
                                students.Add(new Student(sno, name, city, totalMarks)); 
                            break;

case 2:
                            updateStudent(); break;

case 3:
                            deleteStudent(); break;

case 4:
                            enterSno();
                            viewStudent(sno); break;

case 5:
                            viewAllStudents(); break;

case 6:
                            viewStudentResult(); break;

case 7:
                            return;

default:
                            Console.Write("\nInvalid Choice, Please enter a valid choice");
                            break;
                    }

do
                    {
                        Console.Write("\n\nDo you want to continue to the Application, Say (yes or no)");
                        ch = Console.ReadLine().Trim().ToLower();

if(ch != "yes" && ch != "no")
                            Console.Write("\n\nInvalid Choice, Please say (yes or no)");

}while(ch != "yes" && ch != "no");
                }

}while(ch == "yes");

Console.WriteLine("\n\n  *** Program Terminated *** ");     
        }
        
        public static void enterDetails()
        {
            Console.WriteLine("\n\nPlease provide the details below");
            Console.WriteLine("+++++++++++++++++++++++++++++++++");
            
            enterSno();
            enterName();
            enterCity();
            enterTotalMarks();
                        
        }
        
        public static void enterSno()
        {
            Console.Write("\nEnter Sno : ");
            bool IsConversionSuccessful = int.TryParse(Console.ReadLine(), out sno);

if(!IsConversionSuccessful)
               Console.Write("\nPlease enter a valid format");  
        }
        
        public static void enterName()
        {
            Console.Write("\nEnter Name : ");
            name = Console.ReadLine().ToLower();   
        }
        
        public static void enterCity()
        {
            Console.Write("\nEnter City : ");
            city = Console.ReadLine().ToLower(); 
        }
        
        public static void enterTotalMarks()
        {
            Console.Write("\nEnter Total Marks : ");
            bool IsConversionSuccessful = int.TryParse(Console.ReadLine(), out totalMarks);

if(!IsConversionSuccessful)
               Console.Write("\nPlease enter a valid format"); 
        }
        
        
        public static void updateStudent()
        {
            enterDetails();
            Student student = students.Find(x => x.sno == sno && x.name == name && x.city == city && x.totalMarks == totalMarks);
            
            if(student == null)
                Console.Write("\n\n\t *No matchng records found...");

else
            {
                Console.WriteLine("\n\nStudent Details");
                Console.WriteLine("++++++++++++++++++");
                Console.WriteLine($"Sno : {student.sno}\nName : {student.name}\nCity : {student.city}\nTotal Marks : {student.totalMarks}");
                
                Console.WriteLine("\n1. Update Sno\n2. Update Name\n3. Update City\n4. Update Total Marks\n");
                string ch = "";
                
                do
                {
                    Console.Write("\nSelect the property which you want to update : ");
                    int choice = 0;
                    bool IsConversionSuccessful = int.TryParse(Console.ReadLine(), out choice);
                    
                    if(!IsConversionSuccessful)
                       Console.Write("\nPlease enter a valid format"); 
                    else
                    {

switch(choice)
                        {
                            case 1:
                                enterSno();
                                if(sno != 0)
                                {
                                    bool exists = students.Exists(x => x.sno == sno);
                                    if(exists)
                                        Console.Write("\n\n *Sno already exists");
                                    else
                                        student.sno = sno;
                                }
                                break;

case 2:
                                enterName();
                                student.name = name; break;

case 3:
                                enterCity();
                                student.city = city; break;

case 4:
                                enterTotalMarks();
                                if(totalMarks != 0)
                                    student.setTotalMarks(totalMarks); 
                                break;

default:
                                Console.WriteLine("\nInvalid Choice"); break;
                        }

do
                        {
                            Console.WriteLine("\n\nDo you want to continue to update more.., Say (yes or no)");
                            ch = Console.ReadLine().Trim().ToLower();

if(ch != "yes" && ch != "no")
                                Console.Write("\n\nInvalid Choice, Please say (yes or no)");

}while(ch != "yes" && ch != "no");
                    }
                }while(ch == "yes");   
            }        
        }
         
        public static void deleteStudent()
        {
            enterSno();
            Student student = students.Find(x => x.sno == sno);
            
            bool res = students.Remove(student);
            
            if(res)
                Console.Write($"\n  *{student.sno}* removed successfully !!");
            else
                Console.Write("\n\n\t *No matching records found...");

}
        
        public static Student viewStudent(int sno)
        {
            Student student = students.Find(x => x.sno == sno);
            
            if(student == null)
            {
                Console.WriteLine("\n\n\t *No matchng records found...");
                return null;
            }
            else
            {
                Console.WriteLine("\n\nStudent Details");
                Console.WriteLine("++++++++++++++++++");

Console.WriteLine($"Sno : {student.sno}\nName : {student.name}\nCity : {student.city}\nTotal Marks : {student.totalMarks}");
                
                return student;
            }
            
        }
        
        public static void viewAllStudents()
        {
            Console.WriteLine("\n\nStudents Details");
            Console.WriteLine("++++++++++++++++++");
            
            if(students.Count == 0)
                Console.Write("\n0 records");
            else
            {
                int counter = 0;
                foreach(Student student in students)
                {
                    Console.WriteLine($"{counter++}.\tSno : {student.sno}\n\tName : {student.name}\n\tCity : {student.city}\n\tTotal Marks : {student.totalMarks}\n");
                }
            }
        
        }
        
        public static void viewStudentResult()
        {
            enterSno();
            
            Student student = viewStudent(sno);
            
            if(student != null)
            {
                if(student.totalMarks >= 75)
                    Console.WriteLine("Result : First Class");
                else if(student.totalMarks >= 50)
                    Console.WriteLine("Result : Second Class");
                else if(student.totalMarks >= 35)
                    Console.WriteLine("Result : Third Class");
                else
                    Console.WriteLine("Result : Fail");
            }  
        }   
    }
}

Show compiler warnings [ - ] Show input
Compilation time: 2,34 sec, absolute running time: 0,11 sec, cpu time: 0,09 sec, average memory usage: 15 Mb, average nr of threads: 3, absolute service time: 2,48 sec