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Defining Implicit Conversion Routines

Thus far, you have created various custom explicit conversion operations. However, what about the

following 

implicit conversion?

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static void Main(string[] args)

{

...

// Attempt to make an implicit cast?

Square s3;

s3.Length = 83;

Rectangle rect2 = s3;

Console.ReadLine();

}

This code will not compile, given that you have not provided an implicit conversion routine for

the Rectangle type. Now here is the catch: it is illegal to define explicit and implicit conversion func-

tions on the same type, if they do not differ by their return type or parameter set. This might seem

like a limitation; however, the second catch is that when a type defines an implicit conversion rou-

tine, it is legal for the caller to make use of the explicit cast syntax!

Confused? To clear things up, let’s add an implicit conversion routine to the Rectangle struc-

ture using the C# implicit keyword (note that the following code assumes the width of the resulting

Rectangle is computed by multiplying the side of the Square by 2):

public struct Rectangle

{

...

public static implicit operator Rectangle(Square s)

{

Rectangle r;

r.Height = s.Length;