How to Compare two objects regardless of data types in vb.net

Question

As the title implies, I want to compare two objects whose type may be diffrent.

For eg, I expects 'true' for comparing 1000.0(Decimal) with 1000(Double) . Similary, it should return true if I compare 10(string) and 10(double) .

I tried to compare using Object.Equals() , but it did NOT work.It return false if two objects have different data types.

Dim oldVal As Object  ' assgin some value
Dim newVal As Object  'assgin some value
If Not Object.Equals(oldVal,newVal) Then
  'do something
End If

Edit: Could it be possible if I do the below?

    1.check the type of oldVal
    2.Covert the type of newVal to oldVal
    3.Compare.

Answer 1

Mixing pears and apples? :) Equals does equality comparison (the eefault implementation of Equals tests for referential equality). While "=" does identity comparison.

If you need a different behaviour for comparing two objects, then define an Equals method and/or a CompareTo method.

To compare integers with doubles, you have to (implicitly or explicitly) convert one of the two operands.

dim i as integer = 1000
dim d as double = 1000.0

return i = CInt(d)

Answer 2

Object.Equals considers two value objects equal when they (a) have the same binary representation and (b) are bitwise equal, so basically it will always return false for different value types.

You can try to convert all values to double using Convert.ToDouble and then compare double values, if that suits your task; be ready to catch possible exceptions with conversion though.

Answer 3

You've basically described the standard behaviour of VB.Net if you use Option Strict Off? So just use Option Strict Off and then write a = b

In fact I recommend you do not do this as it is very likely to introduce bugs :) Can you explain why you need this behaviour?

Answer 4

there are a couple of ways you could do this, below is the one i feel that is closest to what you're looking for, though personally I dont think its a good way to structure your solution.

Dim fooObj As New Foo
Dim barObj As New Bar

fooObj.Value = 10
barObj.Value = 10

System.Diagnostics.Debug.WriteLine(barObj.Equals(fooObj))
System.Diagnostics.Debug.WriteLine(barObj.Equals(barObj))
System.Diagnostics.Debug.WriteLine(barObj.Equals(10))
System.Diagnostics.Debug.WriteLine(barObj.Equals(20))
System.Diagnostics.Debug.WriteLine(barObj.Equals("10"))
System.Diagnostics.Debug.WriteLine(barObj.Equals("20"))

System.Diagnostics.Debug.WriteLine(Object.Equals(barObj, 10))

Public Class Foo
    Public Value As Integer
End Class

Public Class Bar
    Public Value As Integer

    Public Overrides Function Equals(ByVal obj As Object) As Boolean

        If TypeOf obj Is Bar Then
            Dim compareBar As Bar = DirectCast(obj, Bar)

            Return MyClass.Value = compareBar.Value

        ElseIf TypeOf obj Is Foo Then
            Dim compareFoo As Foo = DirectCast(obj, Foo)

            Return MyClass.Value = compareFoo.Value

        ElseIf TypeOf obj Is Integer Then
            Dim compareInt As Integer = DirectCast(obj, Integer)

            Return MyClass.Value = compareInt

        ElseIf TypeOf obj Is String Then
            Dim compareString As String = DirectCast(obj, String)

            Return MyClass.Value.ToString() = compareString
        End If



        Return False

    End Function
End Class