Convert.ToChar Method (String, IFormatProvider)

Parameters

• value
  Type: System.String
  A String of length 1 or nulla null reference (Nothing in Visual Basic).

• provider
  Type: System.IFormatProvider
  (Reserved) An IFormatProvider interface implementation that supplies culture-specific formatting information.

Return Value

Type: System.Char
The Unicode character equivalent to the first and only character in value.

' Example of selected Convert.ToXXX( String, IFormatProvider ) methods.
Imports System.Globalization

Public Class DummyProvider
   Implements IFormatProvider

   ' Normally, GetFormat returns an object of the requested type
   ' (usually itself) if it is able; otherwise, it returns Nothing. 
   Public Function GetFormat(ByVal argType As Type) As Object _
       Implements IFormatProvider.GetFormat

      ' Here, GetFormat displays the name of argType, after removing 
      ' the namespace information. GetFormat always returns Nothing.
      Dim argStr As String = argType.ToString()
      If argStr = "" Then argStr = "Empty"
      argStr = argStr.Substring(argStr.LastIndexOf("."c) + 1)

      outputBlock.Text &= String.Format("{0,-20}", argStr)
      Return Nothing

   End Function
End Class

Module Example

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Create an instance of IFormatProvider.
      Dim provider As New DummyProvider()
      Dim format As String = "{0,-17}{1,-17}{2}"

      ' Convert these values using DummyProvider.
      Dim Int32A As String = "-252645135"
      Dim DoubleA As String = "61680.3855"
      Dim DayTimeA As String = "2001/9/11 13:45"

      Dim BoolA As String = "True"
      Dim StringA As String = "Qwerty"
      Dim CharA As String = "$"

      outputBlock.Text &= "This example of selected " & _
          "Convert.ToXXX( String, IFormatProvider ) " & vbCrLf & _
          "methods generates the following output. The example " & _
          "displays the " & vbCrLf & "provider type if the " & _
          "IFormatProvider is called." & vbCrLf
      outputBlock.Text &= vbCrLf & _
          "Note: For the ToBoolean, ToString, and ToChar " & _
          "methods, the " & vbCrLf & "IFormatProvider object " & _
          "is not referenced." & vbCrLf

      ' The format provider is called for the following conversions.
      outputBlock.Text &= vbCrLf
      outputBlock.Text &= String.Format(format, "ToInt32", Int32A, _
          Convert.ToInt32(Int32A, provider)) & vbCrLf
      outputBlock.Text &= String.Format(format, "ToDouble", DoubleA, _
          Convert.ToDouble(DoubleA, provider)) & vbCrLf
      outputBlock.Text &= String.Format(format, "ToDateTime", DayTimeA, _
          Convert.ToDateTime(DayTimeA, provider)) & vbCrLf

      ' The format provider is not called for these conversions.
      outputBlock.Text &= vbCrLf
      outputBlock.Text &= String.Format(format, "ToBoolean", BoolA, _
          Convert.ToBoolean(BoolA, provider)) & vbCrLf
      outputBlock.Text &= String.Format(format, "ToString", StringA, _
          Convert.ToString(StringA, provider)) & vbCrLf
      outputBlock.Text &= String.Format(format, "ToChar", CharA, _
          Convert.ToChar(CharA, provider)) & vbCrLf

   End Sub
End Module

' This example of selected Convert.ToXXX( String, IFormatProvider )
' methods generates the following output. The example displays the
' provider type if the IFormatProvider is called.
'
' Note: For the ToBoolean, ToString, and ToChar methods, the
' IFormatProvider object is not referenced.
' 
' NumberFormatInfo    ToInt32          -252645135       -252645135
' NumberFormatInfo    ToDouble         61680.3855       61680.3855
' DateTimeFormatInfo  ToDateTime       2001/9/11 13:45  9/11/2001 1:45:00 PM
' 
' ToBoolean        True             True
' ToString         Qwerty           Qwerty
' ToChar           $                $

// Example of selected Convert.ToXXX( String, IFormatProvider ) methods.
using System;
using System.Globalization;

public class DummyProvider : IFormatProvider
{
   private System.Windows.Controls.TextBlock outputBlock;

   public DummyProvider(System.Windows.Controls.TextBlock outputBlock)
   {
      this.outputBlock = outputBlock;
   }

   // Normally, GetFormat returns an object of the requested type
   // (usually itself) if it is able; otherwise, it returns Nothing. 
   public object GetFormat(Type argType)
   {
      // Here, GetFormat displays the name of argType, after removing 
      // the namespace information. GetFormat always returns null.
      string argStr = argType.ToString();
      if (argStr == "")
         argStr = "Empty";
      argStr = argStr.Substring(argStr.LastIndexOf('.') + 1);

      outputBlock.Text += String.Format("{0,-20}", argStr);
      return null;
   }
}

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // Create an instance of IFormatProvider.
      DummyProvider provider = new DummyProvider(outputBlock);
      string format = "{0,-17}{1,-17}{2}";

      // Convert these values using DummyProvider.
      string Int32A = "-252645135";
      string DoubleA = "61680.3855";
      string DayTimeA = "2001/9/11 13:45";

      string BoolA = "True";
      string StringA = "Qwerty";
      string CharA = "$";

      outputBlock.Text += "This example of selected " +
          "Convert.ToXXX( String, IFormatProvider ) \nmethods " +
          "generates the following output. The example displays " +
          "the \nprovider type if the IFormatProvider is called." + "\n";
      outputBlock.Text += "\nNote: For the " +
          "ToBoolean, ToString, and ToChar methods, the \n" +
          "IFormatProvider object is not referenced." + "\n";

      // The format provider is called for the following conversions.
      outputBlock.Text += "\n";
      outputBlock.Text += String.Format(format, "ToInt32", Int32A,
          Convert.ToInt32(Int32A, provider)) + "\n";
      outputBlock.Text += String.Format(format, "ToDouble", DoubleA,
          Convert.ToDouble(DoubleA, provider)) + "\n";
      outputBlock.Text += String.Format(format, "ToDateTime", DayTimeA,
          Convert.ToDateTime(DayTimeA, provider)) + "\n";

      // The format provider is not called for these conversions.
      outputBlock.Text += "\n";
      outputBlock.Text += String.Format(format, "ToBoolean", BoolA,
          Convert.ToBoolean(BoolA, provider)) + "\n";
      outputBlock.Text += String.Format(format, "ToString", StringA,
          Convert.ToString(StringA, provider)) + "\n";
      outputBlock.Text += String.Format(format, "ToChar", CharA,
          Convert.ToChar(CharA, provider)) + "\n";
   }
}

/*
This example of selected Convert.ToXXX( String, IFormatProvider )
methods generates the following output. The example displays the
provider type if the IFormatProvider is called.

Note: For the ToBoolean, ToString, and ToChar methods, the
IFormatProvider object is not referenced.

NumberFormatInfo    ToInt32          -252645135       -252645135
NumberFormatInfo    ToDouble         61680.3855       61680.3855
DateTimeFormatInfo  ToDateTime       2001/9/11 13:45  9/11/2001 1:45:00 PM

ToBoolean        True             True
ToString         Qwerty           Qwerty
ToChar           $                $
*/