How to write an universal function isNegative?

[mynkow]

Hi,

I want to write an universal function called isNegative( param ) where the param can be float, int, double, long etc. The result will be true/false. Any comments?

[shweta123]

Hi,

You can try this code :

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Double
        i = 12.0

        ''Call function to check if no is positive or negative
        If (isNegative(i)) Then
            MsgBox("No is negative")
        Else
            MsgBox("No is Positive")
        End If
    End Sub

    Public Function isNegative(ByVal obj As Object) As Boolean

        If (obj < 0) Then
                   'given no is negative
            Return True
        Else
             'Given no is not negative
            Return False
        End If
    End Function

Is this that you want?

[mynkow]

NO. You cannot compare object type just like that!

[Frinavale]

NO. You cannot compare object type just like that!

You can if the param can be float, int, double, long etc (like you originally asked for)....it'll throw errors if the object cannot be compared in this way.

The alternative to this is to write overloaded function....eg functions with the same name but different signatures:

Private Function isNegative(byval value as float)
'...
End Function

Private Function isNegative(byval value as integer)
'...
End Function
'And so on....

I think the first solution is a bit easier to implement though....and all you have to do is add a Try Catch block around it...

Give it a try and see what happens.

-Frinny

[mynkow]

I am using C# and I get a compile error when I try to do such compare.

Operator '<' cannot be applied to operands of type 'object'.

Also I do not want to create hundreds of functions. I think it is possible with runtime type cast or something like that.

[Frinavale]

I am using C# and I get a compile error when I try to do such compare.

Operator '<' cannot be applied to operands of type 'object'.

Also I do not want to create hundreds of functions. I think it is possible with runtime type cast or something like that.

Sounds good, give it a try.

You can use the TypeOf operator to determine the type of the object passed in...

Then determine if a comparison can be made on the object passed in to determine if it is negative....

If it can be made, use a Switch to make the appropriate comparison on the object after casting it into it's proper type.


-Frinny

[Curtis Rutland]

I am using C# and I get a compile error when I try to do such compare.

Operator '<' cannot be applied to operands of type 'object'.

Also I do not want to create hundreds of functions. I think it is possible with runtime type cast or something like that.

Well, you don't have to write hundreds, since (as far as I know) there are only 7 signed primitive data types: sbyte, short, int, long, float, double, and decimal. It wouldn't be much work to write all seven, just copy, paste, change type, repeat. You can even make a class library, so you can just add the DLL to any project and have these functions.

[Plater]

Course instead of writing out functions you could just do "< 0" whereever you wanted....