The IFormattable Interface : IFormattable « Development « VB.Net Tutorial

1. VB.Net Tutorial
2. Development
3. IFormattable

Imports System.Globalization

Public Class Temperature : Implements IFormattable
   Private m_Temp As Decimal

   Public Sub New(temperature As Decimal)
      Me.m_Temp = temperature
   End Sub

   Public ReadOnly Property Celsius() As Decimal
      Get
         Return Me.m_Temp
      End Get   
   End Property

   Public ReadOnly Property Kelvin() As Decimal
      Get
         Return Me.m_Temp + 273.15d   
      End Get
   End Property

   Public ReadOnly Property Fahrenheit() As Decimal
      Get
         Return Math.Round(CDec(Me.m_Temp * 9 / 5 + 32), 2)
      End Get      
   End Property

   Public Overrides Function ToString() As String
      Return Me.ToString("G", Nothing)
   End Function

   Public Overloads Function ToString(format As String) As String
      Return Me.ToString(format, Nothing)
   End Function

   Public Overloads Function ToString(format As String, provider As IFormatProvider) As String _  
      Implements IFormattable.ToString

      If String.IsNullOrEmpty(format) Then format = "G"
      format = format.Trim().ToUpperInvariant()

      If provider Is Nothing Then provider = NumberFormatInfo.CurrentInfo

      Select Case format
         Case "F"
            Return Me.Fahrenheit.ToString("N2", provider) & "F"
         Case "K"
            Return Me.Kelvin.ToString("N2", provider) & "K"

         Case "C", "G"
            Return Me.Celsius.ToString("N2", provider) & "C"
         Case Else
            Throw New FormatException(String.Format("The '{0}' format string is not supported.", format))
      End Select      
   End Function
End Class

Public Module Example
   Public Sub Main()
      Dim temp1 As New Temperature(22d)
      Console.WriteLine(Convert.ToString(temp1, New CultureInfo("ja-JP")))
      Console.WriteLine("Temperature: {0:K}", temp1)
      Console.WriteLine("Temperature: {0:F}", temp1)
      Console.WriteLine(String.Format(New CultureInfo("fr-FR"), "Temperature: {0:F}", temp1)) 
   End Sub
End Module