API's that Suck

June 1, 2009

Should 0 equal 0.0?

Filed under: Uncategorized — Grauenwolf @ 8:05 pm

Should the integer 0 be equal to the decimal 0.0?

C# says maybe:

int a = (int)0;
decimal b = (decimal)0.0;
Console.WriteLine(a == b); //true
Console.WriteLine(b == a); //true

object boxA = (int)0;
object boxB = (decimal)0.0;
Console.WriteLine(boxA == boxB); //false
Console.WriteLine(boxB == boxA); //false

By contrast, Visual Basic says yes.

Dim a As Integer = CInt(0)
Dim b As Decimal = CDec(0.0)
Console.WriteLine(a = b) 'true
Console.WriteLine(b = a) 'true

Dim boxA As Object = CInt(0)
Dim boxB As Object = CDec(0.0)
Console.WriteLine(boxA = boxB) 'true
Console.WriteLine(boxB = boxA) 'true


The VB code looks like this in C#

Console.WriteLine(RuntimeHelpers.GetObjectValue(Operators.CompareObjectEqual(boxA, boxB, false)));

C# code looks like this in VB

Console.WriteLine((boxA Is boxB))
As you can see, C# assumes that you want == to mean reference equality when dealing with variables of type Object. Meanwhile, VB is using helper functions because it doesn’t automatically trust the Object.Equals(Object) method to be correct.
About these ads

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

The WordPress Classic Theme. Blog at WordPress.com.


Get every new post delivered to your Inbox.

%d bloggers like this: