A more practical demonstration of a base class constraint : Base class constaint « Generic « C# / CSharp Tutorial

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C# / CSharp Tutorial » Generic » Base class constaint 
18.19.2.A more practical demonstration of a base class constraint
using System; 
 
class NotFoundException : ApplicationException {} 
 
class UserID 
  string name; 
  string number; 
 
  public UserID(string n, string num) { 
    name = n; 
    number = num; 
  
 
  public string Number 
    get return number; 
    set number = value; 
  
 
  public string Name 
    get return name; 
    set name = value; 
  

 
class Employee : UserID 
  public Employee(string n, string num: base(n, num
  

  

 
class Manager : UserID 
  public Manager(string n, string num
    base(n, num) { } 

 
class Guest 

 
class IDList<T> where T : UserID 
  T[] userIDList; 
  int end
 
  public IDList() {  
    userIDList = new T[10]
    end 0
  
 
  public bool add(T newEntry) { 
    if(end == 10return false
 
    userIDList[end= newEntry; 
    end++; 
 
    return true
  
 
  public T findByName(string name) { 
    for(int i=0; i<end; i++) { 
      if(userIDList[i].Name == name)  
        return userIDList[i]
 
    
    throw new NotFoundException()
  
 
  public T findByNumber(string number) { 
 
    for(int i=0; i<end; i++) { 
      if(userIDList[i].Number == number)  
        return userIDList[i]
    
    throw new NotFoundException()
  

 
class MainClass 
  public static void Main() { 
    IDList<Employee> plist = new IDList<Employee>()
    plist.add(new Employee("T""1"))
    plist.add(new Employee("G""6"))
    plist.add(new Employee("M""5"))
 
    try 
      Employee frnd = plist.findByName("T")
      Console.Write(frnd.Name + ": " + frnd.Number)
    catch(NotFoundException) { 
      Console.WriteLine("Not Found")
    
 
    Console.WriteLine()
 
    IDList<Manager> plist2 = new IDList<Manager>()
    plist2.add(new Manager("G""8"))
    plist2.add(new Manager("C""9"))
    plist2.add(new Manager("N""2"))
 
    try 
      Manager sp = plist2.findByNumber("8")
      Console.WriteLine(sp.Name + ": " + sp.Number)
    catch(NotFoundException) { 
        Console.WriteLine("Not Found")
    
  
}
T: 1
G: 8
18.19.Base class constaint
18.19.1.A simple demonstration of a base class constraint.
18.19.2.A more practical demonstration of a base class constraint
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