CODEWITHSUNDEEP
c#
ozsenegal
ozsenegal

Reputation: 4133

C# Convert interfaces

Cast a class to an interface is the same as convert a Class to another Class in C#?Does box or unboxing occurs in this process?

interface Area
{
   string TxtArea
   {
     get;
     set;
   }
}

Convert to it interface:

public void Test()

    {
       ExternArea extArea = new ExternArea();
       if(extArea is Area)
       {
         ((Area)extArea).TxtArea = "voila";
       }
    }

Upvotes: 2

Views: 445

Answers (4)

JeffFerguson
JeffFerguson

Reputation: 3002

As long as the ExternArea object in your code sample is a reference type, then - no - no boxing operations will be performed. Boxing and unboxing refers to operations undertaken when value types are converted into objects.

For more information, please see Boxing and Unboxing (C# Programming Guide).

Upvotes: 0

steinar
steinar

Reputation: 9653

Boxing and unboxing have to do with packaging a value type inside an object, so it can be used as a reference type (allocated on the heap). When you're unboxing, you're getting such a value back from the "box". So no, this would not occur in this example.

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1500545

Assuming ExternArea is a class rather than a value type (struct or enum), there's no boxing involved. Boxing only ever converts a value type to a reference type instance.

Note that using as is generally preferred though:

Area area = extArea as Area;
if (area != null)
{
    area.TxtArea = "voila";
}

Upvotes: 10

SLaks
SLaks

Reputation: 887453

Boxing only occurs if you convert a value type (a struct or a number) to a reference type (object or an interface implemented by the struct)

Casting a reference type (an instance of a class) to a different reference type (a base class or an interface implemented by the class) does not involve boxing.

Even so, you should not cast unnecessarily; instead, use the as keyword, like this:

Area area = extArea as Area;
if (area != null)
{
    area.TxtArea = "voila";
}

Upvotes: 2

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