C# 0 The Complete Reference

double

 by default), the 

type of 

e

 is 

double

. Had 

e

 been declared like this:

var e = 2.7183F;

then

e

 would have the type 

float

, instead.

The following program demonstrates implicitly typed variables. It reworks the program 

shown in the preceding section so that all variables are implicitly typed.

//  Demonstrate implicitly typed variables.

using System;

class ImplicitlyTypedVar {

  static void Main() {

    // These are now implicitly typed variables. They

    // are of type double because their initializing

    // expressions are of type double.

    var s1 = 4.0;

    var s2 = 5.0;

    // Now, hypot is implicitly typed.  Its type is double

    // because the return type of Sqrt() is double.

    var hypot = Math.Sqrt( (s1 * s1) + (s2 * s2) );

    Console.Write("Hypotenuse of triangle with sides " +

                  s1 + " by " + s2 + " is ");

    Console.WriteLine("{0:#.###}.", hypot);

    // The following statement will not compile because

    // s1 is a double and cannot be assigned a decimal value.

www.freepdf-books.com

---

52

 

P a r t   I :  

T h e   C #   L a n g u a g e

//    s1 = 12.2M;  // Error!

  }

}

The output is the same as before.

It is important to emphasize that an implicitly typed variable is still a strongly typed 

variable. Notice this commented-out line in the program:

//    s1 = 12.2M;  // Error!

This assignment is invalid because