using System;

struct MyStruct {
}

class MyClass {
}

class Test<T> where T : struct {
  T obj;

  public Test(T x) {
    obj = x;
  }
}

class Test {
  public static void Main() {
    Test<MyStruct> x = new Test<MyStruct>(new MyStruct());
    Test<int> y = new Test<int>(10);

    // But, the following declaration is illegal!
//    Test<MyClass> z = new Test<MyClass>(new MyClass());
  }
}
           
          

   


using System;
class MyClass {
}

class Test<T> where T : class {
  T obj;

  public Test() {
    // The following statement is legal only
    // because T is guaranteed to be a reference
    // type, which can be assigned the value null.
    obj = null;
  }
  public void print(){
     Console.WriteLine(obj);
  }
}

class ClassConstraintDemo {
  public static void Main() {

    Test<MyClass> x = new Test<MyClass>();

    // The next line is in error because int is
    // a value type.
//    Test<int> y = new Test<int>();
  }
}
           
          

   
 
using System;
using System.Collections;


public class Starter {
    public static void Main() {
        // MyClass<int> obj1=new MyClass<int>(); [illegal]
        MyClass<XClass> obj2 = new MyClass<XClass>();

    }
}

public class MyClass<T> where T : class {

    public void Iterate(T data) {
    }
}

public class XClass {
}

    

   


using System;

class MyClass {

  public MyClass() {
  }

}

class Test<T> where T : new() {
  T obj;

  public Test() {
    // This works because of the new() constraint.
    obj = new T(); // create a T object
  }
}

class ConsConstraintDemo {
  public static void Main() {

    Test<MyClass> x = new Test<MyClass>();

  }
}
           
          

   


using System;

class NotFoundException : ApplicationException { }

public interface IPhoneNumber {
  string Number {
    get;
    set;
  }

  string Name {
    get;
    set;
  }
}

class Friend : IPhoneNumber {
  string name;
  string number;

  public Friend(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 Supplier : IPhoneNumber {
  string name;
  string number;

  public Supplier(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 EmailFriend {
}

class PhoneList<T> where T : IPhoneNumber {
  T[] phList;
  int end;

  public PhoneList() {
    phList = new T[10];
    end = 0;
  }

  public bool add(T newEntry) {
    if(end == 10) return false;

    phList[end] = newEntry;
    end++;

    return true;
  }

  public T findByName(string name) {

    for(int i=0; i<end; i++) {

      if(phList&#91;i&#93;.Name == name)
        return phList&#91;i&#93;;

    }
    throw new NotFoundException();
  }
  public T findByNumber(string number) {

    for(int i=0; i<end; i++) {
      if(phList&#91;i&#93;.Number == number)
        return phList&#91;i&#93;;
    }
    throw new NotFoundException();
  }
}

class Test {
  public static void Main() {

    PhoneList<Friend> plist = new PhoneList<Friend>();
    plist.add(new Friend("A", "555-1111"));
    plist.add(new Friend("B", "555-6666"));
    plist.add(new Friend("C", "555-9999"));

    try {
      Friend frnd = plist.findByName("B");

      Console.Write(frnd.Name + ": " + frnd.Number);

    } catch(NotFoundException) {
      Console.WriteLine("Not Found");
    }

    Console.WriteLine();

    PhoneList<Supplier> plist2 = new PhoneList<Supplier>();
    plist2.add(new Supplier("D", "555-4444"));
    plist2.add(new Supplier("E", "555-3333"));
    plist2.add(new Supplier("F", "555-2222"));

    try {
      Supplier sp = plist2.findByNumber("555-2222");
      Console.WriteLine(sp.Name + ": " + sp.Number);
    } catch(NotFoundException) {
        Console.WriteLine("Not Found");
    }

    //PhoneList<EmailFriend> plist3 = new PhoneList<EmailFriend>(); 
  }
}
           
          

   


using System;

class MyBase {
  public void hello() {
    Console.WriteLine("Hello");
  }
}

class B : MyBase { }

class C { }

class Test<T> where T : MyBase {
  T obj;

  public Test(T o) {
    obj = o;
  }

  public void sayHello() {
    obj.hello();
  }
}

class BaseClassConstraintDemo {
  public static void Main() {
    MyBase a = new MyBase();
    B b = new B();
    C c = new C();

    Test<MyBase> t1 = new Test<MyBase>(a);

    t1.sayHello();

    Test<B> t2 = new Test<B>(b);

    t2.sayHello();

    // The following is invalid because
    // C does not inherit MyBase.
    // Test<C> t3 = new Test<C>(c); // Error!
  }
}


           
          

   
 

/*
Base Method    Derived Method        Comments

Nongeneric     Generic (open)        Permitted

Nongeneric     Generic (closed)      Permitted

Generic (open) Nongeneric            Not permitted

Generic (open) Generic (open)        Permitted; must use the same type parameters

Generic (open) Generic (closed)      Not permitted

Generic (closed) Nongeneric          Permitted

Generic (closed) Generic (closed)    Permitted

Generic (closed)  Generic (open)     Not permitted
*/