C# 0 The Complete Reference

PART I

C h a p t e r   1 8 :  

G e n e r i c s  

503

PART IPART I

    string str = tgObj.GetObj2();

    Console.WriteLine("value: " + str);

  }

}

The output from this program is shown here:

Type of T is System.Int32

Type of V is System.String

value: 119

value: Alpha Beta Gamma

Notice how 

TwoGen

 is declared:

class TwoGen {

It specifies two type parameters: 

T

 and 

V

, separated by a comma. Because it has two type 

parameters, two type arguments must be specified when a 

TwoGen

 object is created, as 

shown here:

TwoGen tgObj =

  new TwoGen(119, "Alpha Beta Gamma");

In this case, 

int

 is substituted for 

T

 and 

string

 is substituted for 

V

.

Although the two type arguments differ in this example, it is possible for both types to 

be the same. For example, the following line of code is valid:

TwoGen x = new TwoGen("Hello", "Goodbye");

In this case, both 

T

 and 

V

 would be of type 

string

. Of course, if the type arguments were 

always the same, then two type parameters would be unnecessary.