Math.Ceiling, Floor

Often numbers need to be manipulated. We can round a number upwards to the nearest integer (with a ceiling function), or down with a floor function.

With VB.NET methods, these functions are available without any development work. We invoke Math.Ceiling and Floor, often with Doubles with fractional parts.

Ceiling example

To begin we use the Math.Ceiling function. We pass in Double values and Ceiling returns a Double. Ceiling always changes a fractional value to be the higher integer.

Module Module1

    Sub Main()
        ' Ceiling returns the next highest integer if a fraction part exists.
        Dim result As Double = Math.Ceiling(1.23)
        Console.WriteLine("CEILING 1.23: " + result.ToString)

        Dim result2 As Double = Math.Ceiling(-1.23)
        Console.WriteLine("CEILING -1.23: " + result2.ToString)

        Dim result3 As Double = Math.Ceiling(1)
        Console.WriteLine("CEILING 1: " + result3.ToString)
    End Sub

End Module
CEILING 1.23: 2
CEILING -1.23: -1
CEILING 1: 1

Floor example

With floor, we change a number with a fractional part to be the lower integer. Even a number like 1.99 is changed to 1. And integers are left unchanged.

Module Module1

    Sub Main()
        ' Floor changes a number to the lower integer if a fraction part is present.
        Dim floor As Double = Math.Floor(1.99)
        Console.WriteLine("FLOOR 1.99: " + floor.ToString)

        Dim floor2 As Double = Math.Floor(-1.99)
        Console.WriteLine("FLOOR -1.99: " + floor2.ToString)
    End Sub

End Module
FLOOR 1.99: 1
FLOOR -1.99: -2

Ceiling and Floor are important functions in the .NET Framework. We rarely need to implement these mathematical methods—we use the reliable ones contained in the Framework.