Is there any difference between Integer and Int32

Question

In VB.NET, is there any difference between Integer and Int32?

If yes, please explain.

Answer 1

Functionally, there is no difference between the types Integer and System.Int32. In VB.NET Integer is just an alias for the System.Int32 type.

The identifiers Int32 and Integer are not completely equal though. Integer is always an alias for System.Int32 and is understood by the compiler. Int32 though is not special cased in the compiler and goes through normal name resolution like any other type. So it's possible for Int32 to bind to a different type in certain cases. This is very rare though; no one should be defining their own Int32 type.

Here is a concrete repro which demonstrates the difference.

Class Int32

End Class

Module Module1
    Sub Main()
        Dim local1 As Integer = Nothing
        Dim local2 As Int32 = Nothing
        local1 = local2 ' Error!!! 
    End Sub
End Module

In this case local1 and local2 are actually different types, because Int32 binds to the user defined type over System.Int32.