declare a variable calss with dim

Question

why we can't declare a variable on some class such as math

for example?

 

dim s as new math

?

but we should imports them..

Answer 1

Because there's no need to; all members are shared (static);

you can go ahead and use all these functions e.g. debug.print(math.Sin(x).ToString)

Answer 2

I'm assuming you are wanting to use these functions

http://msdn.microsoft.com/en-us/library/system.math.aspx

 

Use of imports statement will enable you to use the functions without fully qualifying them  (ie. Having to type System.Math.??????)

But as the documentation states

"Provides constants and static methods....."

So there is no need to create an instance of this class.   This is similar to if the methods were to be declared in a Module in VB.  You don't need to instance a new module to use the methods.

 

Answer 3

Hi spotty,

Another way I'm reading the OP question is;

"Why has the MATH class got no constructor method and doesn't require an instance object"?

 

I.E: Even though System.Math as a CLASS has SHARED methods by what mechanism is the constructor hidden please?

Is it an attribute on the NEW method or the opening line of the CLASS itself?

Intellisense states; "Type System.Math has no constructors."

if you mouse-over the "s" should actually try;

Dim s As New Math

Yet something like this still works in VB.Net ( 2008 ):>>

 

 

Option Strict On
Option Explicit On
Option Infer Off

Public Class Form1

 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

  Dim s As Math
  Dim result As Integer = s.Abs(-34)
  MessageBox.Show(result.ToString)

 End Sub

End Class

 

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Regards,

John

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Answer 4

I believe that this example will provide you with a warning

• Unused local variable: 's'. 
• Access of shared member, constant member, enum member or nested type through an instance; qualifying expression will not be evaluated. 

Both indicate your not using an instance (S has been instantiated anywhere) as such - and are calling the shared member through an instance.

The warnings are highlighting potential flaws in the code.

 

 

Answer 5

why this code work correctly?

 

 Dim s As Math
 Dim result As Integer = s.Abs(-34)






if we assume the math class doesn't have no constructors.it opposite to that vb create a hidden new
 constructors. and why we can declare a variable on math class without new 
constructors?
 

Answer 6

The warnings are telling you that its not using the instance in order to execute the