Addition of Double values inconsistent

Question

I came across following issue while developing some engineering rule value engine using eval(...) implementation.

    Dim first As Double = 1.1
    Dim secon         


        

Answer 1

that's how the double number work in PC. The best way to compare them is to use such a construction

if (Math.Abs(second - first) <= 1E-9)
 Console.WriteLine("Matched")

instead if 1E-9 you can use another number, that would represent the possible error in comparison.