C # compiling platform for student management system

Using System; Using System.Collections.Generic; Using System.Text; Using System.Collections; namespace Studenmanager {struct Student {public int id; public string name: public int age; public string sex;} class M Anager {Student Stu = new Student (); ArrayList list = new ArrayList (); public void Menu () {Console.WriteLine ("1") Add student Information 2. Query student Information 3. Revise student Information 4. Delete Student Information 5. Exit system "); int messager = Int. Parse (Console.ReadLine ()); while (true) {switch (messager) {case 1:addstudent (stu), break, Case 2://console.clear (); Res (Stu); Break Case 3:idupdate (list); Break Case 4:del (list); Break Case 5:ret (); Break }//break; } public void Addstudent (student stu) {a:console.clear (); Console.WriteLine ("Please enter student number:"); stu.id = Int. Parse (Console.ReadLine ()); Console.WriteLine ("Please enter student name:"); Stu.name = Console.ReadLine (); Console.WriteLine ("Please enter the student's Age:"); stu.age = Int. Parse (Console.ReadLine ()); Console.WriteLine ("Please enter the student's gender:"); Stu.sex = Console.ReadLine (); List. ADD (Stu); Console.WriteLine ("Add success!") "); ConsolE.writeline ("1. Continue to add 2. Return to main Menu"); int sel = Int. Parse (Console.ReadLine ()); Switch (SEL) {case 1:goto A; case 2:console.clear (); Menu (); Break The public void Res (student stu) {Console.WriteLine ("1. Query 2 by study number 3. Query by name); int messager = Int. Parse (Console.ReadLine ()); Switch (messager) {case 1:fullres (list), break, Case 2:idres (list), break, Case 3:nameres (list), break;}} public void Fullres (ArrayList list) {foreach (Student stu in list) {Console.WriteLine (stu.id + "" + Stu.name + "" + St U.age + "" + Stu.sex);} Console.ReadLine (); Console.clear (); Menu (); } public void Idres (ArrayList list) {Console.WriteLine ("Enter the student ID to query:"); int id = Int. Parse (Console.ReadLine ()); foreach (Student stu in list) {if (ID). Equals (Stu.id)) Console.WriteLine (Stu.id + "" + Stu.name + "" + Stu.age + "" + Stu.sex + "" + list. IndexOf (Stu)); } console.readline (); Console.clear (); Menu (); } public void Nameres (ArrayList list) {Console.WriteLine ("Enter the name of the student to query:"); string name = Console.ReadLine (); foreach (Student stu in list) {if (name). Equals (Stu.name)) Console.WriteLine (stu.id + "+ stu.name +" &quo