C# Convert ChangeType(Object, TypeCode, IFormatProvider)

Description

Convert ChangeType(Object, TypeCode, IFormatProvider) returns an object of the specified type whose value is equivalent to the specified object. A parameter supplies culture-specific formatting information.

Syntax

Convert.ChangeType(Object, TypeCode, IFormatProvider) has the following syntax.


public static Object ChangeType(
  Object value,//w  ww  .j av  a  2  s.c o  m
  TypeCode typeCode,
  IFormatProvider provider
)

Parameters

Convert.ChangeType(Object, TypeCode, IFormatProvider) has the following parameters.

value - An object that implements the IConvertible interface.
typeCode - The type of object to return.
provider - An object that supplies culture-specific formatting information.

Returns

Convert.ChangeType(Object, TypeCode, IFormatProvider) method returns An object whose underlying type is typeCode and whose value is equivalent to value. -or- A null reference (Nothing in Visual Basic), if value is null and typeCode is Empty, String, or Object.

Example

The following example defines a custom format provider named InterceptProvider that indicates when its GetFormat method is called and returns a NumberFormatInfo for the fr-FR culture and a DateTimeFormatInfo object for the en-US culture.


/*from   w ww.jav  a2 s  .  c  om*/
using System;
using System.Globalization;

public class InterceptProvider : IFormatProvider
{
   public object GetFormat(Type formatType) 
   {
      if (formatType == typeof(NumberFormatInfo)) {
         Console.WriteLine("   Returning a fr-FR numeric format provider.");
         return new System.Globalization.CultureInfo("fr-FR").NumberFormat;
      }   
      else if (formatType == typeof(DateTimeFormatInfo)) {
         Console.WriteLine("   Returning an en-US date/time format provider.");
         return new System.Globalization.CultureInfo("en-US").DateTimeFormat;
      }
      else {
         Console.WriteLine("   Requesting a format provider of {0}.", formatType.Name);
         return null;
      }
   }
}

public class Example
{
   public static void Main()
   {
      object[] values = { 103.5d, new DateTime(2010, 12, 26, 14, 34, 0) };
      IFormatProvider provider = new InterceptProvider();

      foreach (object value in values)
      {
         foreach (TypeCode enumType in ((TypeCode[]) Enum.GetValues(typeof(TypeCode))))
         {         
            try {
               Console.WriteLine("{0} ({1}) --> {2} ({3}).", 
                                 value, value.GetType().Name,
                                 Convert.ChangeType(value, enumType, provider),
                                 enumType.ToString());
            }                     
            catch (Exception) {
               Console.WriteLine("Exception");
            }
         }
      }
   }
}

The code above generates the following result.