Convert.ChangeType Methode
Definition
Gibt ein Objekt eines angegebenen Typs zurück, dessen Wert einem angegebenen Objekt entspricht.Returns an object of a specified type whose value is equivalent to a specified object.
Überlädt
ChangeType(Object, Type) |
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type and whose value is equivalent to the specified object. |
ChangeType(Object, TypeCode) |
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object. |
ChangeType(Object, Type, IFormatProvider) |
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object. Ein Parameter liefert kulturspezifische Formatierungsinformationen.A parameter supplies culture-specific formatting information. |
ChangeType(Object, TypeCode, IFormatProvider) |
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object. Ein Parameter liefert kulturspezifische Formatierungsinformationen.A parameter supplies culture-specific formatting information. |
ChangeType(Object, Type)
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type and whose value is equivalent to the specified object.
public:
static System::Object ^ ChangeType(System::Object ^ value, Type ^ conversionType);
public static object ChangeType (object value, Type conversionType);
public static object? ChangeType (object? value, Type conversionType);
static member ChangeType : obj * Type -> obj
Public Shared Function ChangeType (value As Object, conversionType As Type) As Object
Parameter
- value
- Object
Ein Objekt, das die IConvertible-Schnittstelle implementiert.An object that implements the IConvertible interface.
- conversionType
- Type
Der Typ des zurückzugebenden Objekts.The type of object to return.
Gibt zurück
Ein Objekt, dessen Typ conversionType
ist und dessen Wert value
entspricht.An object whose type is conversionType
and whose value is equivalent to value
.
- oder --or-
Ein Nullverweis (Nothing
in Visual Basic), wenn value
null
ist und conversionType
kein Werttyp.A null reference (Nothing
in Visual Basic), if value
is null
and conversionType
is not a value type.
Ausnahmen
Diese Konvertierung wird nicht unterstützt.This conversion is not supported.
- oder --or-
value
ist null
, und conversionType
ist ein Werttyp.value
is null
and conversionType
is a value type.
- oder --or-
Die IConvertible-Schnittstelle wird von value
nicht implementiert.value
does not implement the IConvertible interface.
value
hat ein Format, das von conversionType
nicht erkannt wird.value
is not in a format recognized by conversionType
.
value
stellt eine Zahl außerhalb des Bereichs von conversionType
dar.value
represents a number that is out of the range of conversionType
.
conversionType
ist null
.conversionType
is null
.
Beispiele
Im folgenden Beispiel wird die Verwendung der ChangeType-Methode veranschaulicht.The following example illustrates the use of the ChangeType method.
using namespace System;
int main()
{
Double d = -2.345;
int i = *safe_cast<Int32^>(Convert::ChangeType( d, int::typeid ));
Console::WriteLine( "The double value {0} when converted to an int becomes {1}", d, i );
String^ s = "12/12/98";
DateTime dt = *safe_cast<DateTime^>(Convert::ChangeType( s, DateTime::typeid ));
Console::WriteLine( "The string value {0} when converted to a Date becomes {1}", s, dt );
}
using System;
public class ChangeTypeTest {
public static void Main() {
Double d = -2.345;
int i = (int)Convert.ChangeType(d, typeof(int));
Console.WriteLine("The double value {0} when converted to an int becomes {1}", d, i);
string s = "12/12/98";
DateTime dt = (DateTime)Convert.ChangeType(s, typeof(DateTime));
Console.WriteLine("The string value {0} when converted to a Date becomes {1}", s, dt);
}
}
Public Class ChangeTypeTest
Public Shared Sub Main()
Dim d As [Double] = - 2.345
Dim i As Integer = CInt(Convert.ChangeType(d, GetType(Integer)))
Console.WriteLine("The double value {0} when converted to an int becomes {1}", d, i)
Dim s As String = "12/12/98"
Dim dt As DateTime = CType(Convert.ChangeType(s, GetType(DateTime)), DateTime)
Console.WriteLine("The string value {0} when converted to a Date becomes {1}", s, dt)
End Sub
End Class
Hinweise
ChangeType ist eine allgemeine Konvertierungsmethode, die das von angegebene Objekt value
in konvertiert conversionType
.ChangeType is a general-purpose conversion method that converts the object specified by value
to conversionType
. Der value
-Parameter kann ein Objekt eines beliebigen Typs sein, und es conversionType
kann sich auch um ein-Objekt handeln, das einen Type beliebigen Basis-oder benutzerdefinierten Typ darstellt.The value
parameter can be an object of any type, and conversionType
can also be a Type object that represents any base or custom type. Damit die Konvertierung erfolgreich durchgeführt werden kann, value
muss die- IConvertible Schnittstelle implementieren, da die-Methode einfach einen aufzurufenden-Methode umschließt IConvertible .For the conversion to succeed, value
must implement the IConvertible interface, because the method simply wraps a call to an appropriate IConvertible method. Die-Methode erfordert, dass die Konvertierung von value
in conversionType
unterstützt wird.The method requires that conversion of value
to conversionType
be supported.
Diese Methode verwendet die Kultur des aktuellen Threads für die Konvertierung.This method uses the current thread's culture for the conversion.
Hinweise für Aufrufer
Die- ChangeType(Object, Type) Methode kann einen Enumerationswert in einen anderen Typ konvertieren.The ChangeType(Object, Type) method can convert an enumeration value to another type. Es ist jedoch nicht möglich, einen anderen Typ in einen Enumerationswert zu konvertieren, auch wenn der Quelltyp der zugrunde liegende Typ der Enumeration ist.However, it cannot convert another type to an enumeration value, even if the source type is the underlying type of the enumeration. Verwenden Sie zum Konvertieren eines Typs in einen Enumerationswert einen Typumwandlungs Operator (in c#) oder eine Konvertierungs Funktion (in Visual Basic).To convert a type to an enumeration value, use a casting operator (in C#) or a conversion function (in Visual Basic). Das folgende Beispiel veranschaulicht die Konvertierung in einen und aus einem Kontinent
-Enumerationswert.The following example illustrates the conversion to and from a Continent
enumeration value.
::: Code language = "CSharp" Source = "~/Samples/Snippets/CSharp/VS_Snippets_CLR_System/System.Convert.ChangeType/CS/changetype_enum2. cs" Interactive = "try-dotnet" ID = "Snippet5":::::: Code language = "vb" Source = "~/Samples/Snippets/VisualBasic/VS_Snippets_CLR_System/System.Convert.ChangeType/VB/changetype_enum2. vb" ID = "Snippet5"::::::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR_System/system.convert.changetype/cs/changetype_enum2.cs" interactive="try-dotnet" id="Snippet5"::: :::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.convert.changetype/vb/changetype_enum2.vb" id="Snippet5":::
Die ChangeType(Object, Type) Methode kann einen Typ, der NULL-Werte zulässt, in einen anderen Typ konvertieren.The ChangeType(Object, Type) method can convert a nullable type to another type. Es ist jedoch nicht möglich, einen anderen Typ in einen Wert eines Typs zu konvertieren, der NULL-Werte zulässt, auch wenn conversionType
der zugrunde liegende Typ von ist Nullable<T> . Sie können einen Typumwandlungs Operator (in c#) oder eine Konvertierungs Funktion (in Visual Basic) verwenden, um die Konvertierung auszuführen.However, it cannot convert another type to a value of a nullable type, even if conversionType
is the underlying type of the Nullable<T>.To perform the conversion, you can use a casting operator (in C#) or a conversion function (in Visual Basic). Im folgenden Beispiel wird die Konvertierung in einen und aus einem Werte zulässt-Typ veranschaulicht.The following example illustrates the conversion to and from a nullable type.
::: Code language = "CSharp" Source = "~/Samples/Snippets/CSharp/VS_Snippets_CLR_System/System.Convert.ChangeType/CS/changetype_nullable. cs" Interactive = "try-dotnet" ID = "Snippet7":::::: Code language = "vb" Source = "~/Samples/Snippets/VisualBasic/VS_Snippets_CLR_System/System.Convert.ChangeType/VB/changetype_nullable. vb" ID = "Snippet7"::::::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR_System/system.convert.changetype/cs/changetype_nullable.cs" interactive="try-dotnet" id="Snippet7"::: :::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.convert.changetype/vb/changetype_nullable.vb" id="Snippet7":::
Gilt für:
ChangeType(Object, TypeCode)
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object.
public:
static System::Object ^ ChangeType(System::Object ^ value, TypeCode typeCode);
public static object? ChangeType (object? value, TypeCode typeCode);
public static object ChangeType (object value, TypeCode typeCode);
static member ChangeType : obj * TypeCode -> obj
Public Shared Function ChangeType (value As Object, typeCode As TypeCode) As Object
Parameter
- value
- Object
Ein Objekt, das die IConvertible-Schnittstelle implementiert.An object that implements the IConvertible interface.
- typeCode
- TypeCode
Der Typ des zurückzugebenden Objekts.The type of object to return.
Gibt zurück
Ein Objekt, dem typeCode
als Typ zugrunde liegt und dessen Wert value
entspricht.An object whose underlying type is typeCode
and whose value is equivalent to value
.
- oder --or-
Ein Nullverweis (Nothing
in Visual Basic), wenn value
null
ist und typeCode
Empty, String oder Object ist.A null reference (Nothing
in Visual Basic), if value
is null
and typeCode
is Empty, String, or Object.
Ausnahmen
Diese Konvertierung wird nicht unterstützt.This conversion is not supported.
- oder --or-
value
ist null
, und typeCode
gibt einen Werttyp an.value
is null
and typeCode
specifies a value type.
- oder --or-
Die IConvertible-Schnittstelle wird von value
nicht implementiert.value
does not implement the IConvertible interface.
value
hat ein Format, das vom typeCode
-Typ nicht erkannt wird.value
is not in a format recognized by the typeCode
type.
value
stellt eine Zahl außerhalb des Bereichs des typeCode
-Typs dar.value
represents a number that is out of the range of the typeCode
type.
typeCode
ist ungültig.typeCode
is invalid.
Beispiele
Im folgenden Beispiel wird veranschaulicht, wie die- ChangeType(Object, TypeCode) Methode verwendet wird, um eine Object in den vom-Parameter angegebenen Typ zu ändern TypeCode , sofern möglich.The following example illustrates how to use the ChangeType(Object, TypeCode) method to change an Object to the type specified by the TypeCode parameter, if possible.
using namespace System;
void main()
{
Double d = -2.345;
int i = (int) Convert::ChangeType(d, TypeCode::Int32);
Console::WriteLine("The Double {0} when converted to an Int32 is {1}", d, i);
String^ s = "12/12/2009";
DateTime dt = (DateTime)Convert::ChangeType(s, DateTime::typeid);
Console::WriteLine("The String {0} when converted to a Date is {1}", s, dt);
}
// The example displays the following output:
// The Double -2.345 when converted to an Int32 is -2
// The String 12/12/2009 when converted to a Date is 12/12/2009 12:00:00 AM
using System;
public class ChangeTypeTest {
public static void Main() {
Double d = -2.345;
int i = (int)Convert.ChangeType(d, TypeCode.Int32);
Console.WriteLine("The Double {0} when converted to an Int32 is {1}", d, i);
string s = "12/12/2009";
DateTime dt = (DateTime)Convert.ChangeType(s, typeof(DateTime));
Console.WriteLine("The String {0} when converted to a Date is {1}", s, dt);
}
}
// The example displays the following output:
// The Double -2.345 when converted to an Int32 is -2
// The String 12/12/2009 when converted to a Date is 12/12/2009 12:00:00 AM
Public Class ChangeTypeTest
Public Shared Sub Main()
Dim d As [Double] = - 2.345
Dim i As Integer = CInt(Convert.ChangeType(d, TypeCode.Int32))
Console.WriteLine("The Double {0} when converted to an Int32 is {1}", d, i)
Dim s As String = "12/12/2009"
Dim dt As DateTime = CDate(Convert.ChangeType(s, TypeCode.DateTime))
Console.WriteLine("The String {0} when converted to a Date is {1}", s, dt)
End Sub
End Class
' The example displays the following output:
' The Double -2.345 when converted to an Int32 is -2
' The String 12/12/2009 when converted to a Date is 12/12/2009 12:00:00 AM
Hinweise
ChangeType(Object, TypeCode) ist eine allgemeine Konvertierungsmethode, die das durch angegebene Objekt value
in einen vordefinierten Typ konvertiert, der durch angegeben wird typeCode
.ChangeType(Object, TypeCode) is a general-purpose conversion method that converts the object specified by value
to a predefined type specified by typeCode
. Der- value
Parameter kann ein Objekt eines beliebigen Typs sein.The value
parameter can be an object of any type. Damit die Konvertierung erfolgreich durchgeführt werden kann, value
muss die- IConvertible Schnittstelle implementieren, da die-Methode einfach einen aufzurufenden-Methode umschließt IConvertible .For the conversion to succeed, value
must implement the IConvertible interface, because the method simply wraps a call to an appropriate IConvertible method. Die-Methode erfordert auch, dass die Konvertierung von value
in typeCode
unterstützt wird.The method also requires that conversion of value
to typeCode
be supported.
Die- ChangeType(Object, TypeCode) Methode unterstützt nicht die Konvertierung von value
in einen benutzerdefinierten Typ.The ChangeType(Object, TypeCode) method does not support the conversion of value
to a custom type. Um eine solche Konvertierung auszuführen, wird die- ChangeType(Object, Type) Methode aufgerufen.To perform such a conversion, call the ChangeType(Object, Type) method.
Gilt für:
ChangeType(Object, Type, IFormatProvider)
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object. Ein Parameter liefert kulturspezifische Formatierungsinformationen.A parameter supplies culture-specific formatting information.
public:
static System::Object ^ ChangeType(System::Object ^ value, Type ^ conversionType, IFormatProvider ^ provider);
public static object ChangeType (object value, Type conversionType, IFormatProvider provider);
public static object? ChangeType (object? value, Type conversionType, IFormatProvider? provider);
static member ChangeType : obj * Type * IFormatProvider -> obj
Public Shared Function ChangeType (value As Object, conversionType As Type, provider As IFormatProvider) As Object
Parameter
- value
- Object
Ein Objekt, das die IConvertible-Schnittstelle implementiert.An object that implements the IConvertible interface.
- conversionType
- Type
Der Typ des zurückzugebenden Objekts.The type of object to return.
- provider
- IFormatProvider
Ein Objekt, das kulturspezifische Formatierungsinformationen bereitstellt.An object that supplies culture-specific formatting information.
Gibt zurück
Ein Objekt, dessen Typ conversionType
ist und dessen Wert value
entspricht.An object whose type is conversionType
and whose value is equivalent to value
.
- oder --or-
value
, wenn der Type von value
und conversionType
gleich sind.value
, if the Type of value
and conversionType
are equal.
- oder --or-
Ein Nullverweis (Nothing
in Visual Basic), wenn value
null
ist und conversionType
kein Werttyp.A null reference (Nothing
in Visual Basic), if value
is null
and conversionType
is not a value type.
Ausnahmen
Diese Konvertierung wird nicht unterstützt.This conversion is not supported.
- oder --or-
value
ist null
, und conversionType
ist ein Werttyp.value
is null
and conversionType
is a value type.
- oder --or-
Die IConvertible-Schnittstelle wird von value
nicht implementiert.value
does not implement the IConvertible interface.
value
hat ein Format für conversionType
, das von provider
nicht erkannt wird.value
is not in a format for conversionType
recognized by provider
.
value
stellt eine Zahl außerhalb des Bereichs von conversionType
dar.value
represents a number that is out of the range of conversionType
.
conversionType
ist null
.conversionType
is null
.
Beispiele
Im folgenden Beispiel wird eine Temperature
-Klasse definiert, die die IConvertible -Schnittstelle implementiert.The following example defines a Temperature
class that implements the IConvertible interface.
using namespace System;
using namespace System::Globalization;
public ref class Temperature : IConvertible
{
private:
Decimal m_Temp;
public:
Temperature(Decimal temperature)
{
m_Temp = temperature;
}
property Decimal Celsius {
Decimal get() { return m_Temp; }
}
property Decimal Kelvin {
Decimal get() { return m_Temp + (Decimal) 273.15; }
}
property Decimal Fahrenheit {
Decimal get() { return Math::Round((Decimal) (m_Temp * 9 / 5 + 32), 2); }
}
virtual String^ ToString()
override {
return m_Temp.ToString("N2") + "�C";
}
// IConvertible implementations.
virtual TypeCode GetTypeCode()
{
return TypeCode::Object;
}
virtual bool ToBoolean(IFormatProvider^ provider)
{
if (m_Temp == 0)
return false;
else
return true;
}
virtual Byte ToByte(IFormatProvider^ provider)
{
if (m_Temp < Byte::MinValue || m_Temp > Byte::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the Byte type.",
m_Temp));
else
return Decimal::ToByte(m_Temp);
}
virtual Char ToChar(IFormatProvider^ provider)
{
throw gcnew InvalidCastException("Temperature to Char conversion is not supported.");
}
virtual DateTime ToDateTime(IFormatProvider^ provider)
{
throw gcnew InvalidCastException("Temperature to DateTime conversion is not supported.");
}
virtual Decimal ToDecimal(IFormatProvider^ provider)
{
return m_Temp;
}
virtual Double ToDouble(IFormatProvider^ provider)
{
return Decimal::ToDouble(m_Temp);
}
virtual Int16 ToInt16(IFormatProvider^ provider)
{
if (m_Temp < Int16::MinValue || m_Temp > Int16::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the Int16 type.",
m_Temp));
else
return Decimal::ToInt16(m_Temp);
}
virtual Int32 ToInt32(IFormatProvider^ provider)
{
if (m_Temp < Int32::MinValue || m_Temp > Int32::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the Int32 type.",
m_Temp));
else
return Decimal::ToInt32(m_Temp);
}
virtual Int64 ToInt64(IFormatProvider^ provider)
{
if (m_Temp < Int64::MinValue || m_Temp > Int64::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the Int64 type.",
m_Temp));
else
return Decimal::ToInt64(m_Temp);
}
virtual SByte ToSByte(IFormatProvider^ provider)
{
if (m_Temp < SByte::MinValue || m_Temp > SByte::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the SByte type.",
m_Temp));
else
return Decimal::ToSByte(m_Temp);
}
virtual Single ToSingle(IFormatProvider^ provider)
{
return Decimal::ToSingle(m_Temp);
}
virtual String^ ToString(IFormatProvider^ provider)
{
return m_Temp.ToString("N2", provider) + "�C";
}
virtual Object^ ToType(Type^ conversionType, IFormatProvider^ provider)
{
switch (Type::GetTypeCode(conversionType))
{
case TypeCode::Boolean:
return ToBoolean(nullptr);
case TypeCode::Byte:
return ToByte(nullptr);
case TypeCode::Char:
return ToChar(nullptr);
case TypeCode::DateTime:
return ToDateTime(nullptr);
case TypeCode::Decimal:
return ToDecimal(nullptr);
case TypeCode::Double:
return ToDouble(nullptr);
case TypeCode::Int16:
return ToInt16(nullptr);
case TypeCode::Int32:
return ToInt32(nullptr);
case TypeCode::Int64:
return ToInt64(nullptr);
case TypeCode::Object:
if (Temperature::typeid->Equals(conversionType))
return this;
else
throw gcnew InvalidCastException(String::Format("Conversion to a {0} is not supported.",
conversionType->Name));
case TypeCode::SByte:
return ToSByte(nullptr);
case TypeCode::Single:
return ToSingle(nullptr);
case TypeCode::String:
return ToString(provider);
case TypeCode::UInt16:
return ToUInt16(nullptr);
case TypeCode::UInt32:
return ToUInt32(nullptr);
case TypeCode::UInt64:
return ToUInt64(nullptr);
default:
throw gcnew InvalidCastException(String::Format("Conversion to {0} is not supported.", conversionType->Name));
}
}
virtual UInt16 ToUInt16(IFormatProvider^ provider)
{
if (m_Temp < UInt16::MinValue || m_Temp > UInt16::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the UInt16 type.",
m_Temp));
else
return Decimal::ToUInt16(m_Temp);
}
virtual UInt32 ToUInt32(IFormatProvider^ provider)
{
if (m_Temp < UInt32::MinValue || m_Temp > UInt32::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the UInt32 type.",
m_Temp));
else
return Decimal::ToUInt32(m_Temp);
}
virtual UInt64 ToUInt64(IFormatProvider^ provider)
{
if (m_Temp < UInt64::MinValue || m_Temp > UInt64::MaxValue)
throw gcnew OverflowException(String::Format("{0} is out of range of the UInt64 type.",
m_Temp));
else
return Decimal::ToUInt64(m_Temp);
}
};
using System;
using System.Globalization;
public class Temperature : IConvertible
{
private decimal m_Temp;
public Temperature(decimal temperature)
{
this.m_Temp = temperature;
}
public decimal Celsius
{
get { return this.m_Temp; }
}
public decimal Kelvin
{
get { return this.m_Temp + 273.15m; }
}
public decimal Fahrenheit
{
get { return Math.Round((decimal) (this.m_Temp * 9 / 5 + 32), 2); }
}
public override string ToString()
{
return m_Temp.ToString("N2") + "°C";
}
// IConvertible implementations.
public TypeCode GetTypeCode()
{
return TypeCode.Object;
}
public bool ToBoolean(IFormatProvider provider)
{
if (m_Temp == 0)
return false;
else
return true;
}
public byte ToByte(IFormatProvider provider)
{
if (m_Temp < Byte.MinValue || m_Temp > Byte.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the Byte type.",
this.m_Temp));
else
return Decimal.ToByte(this.m_Temp);
}
public char ToChar(IFormatProvider provider)
{
throw new InvalidCastException("Temperature to Char conversion is not supported.");
}
public DateTime ToDateTime(IFormatProvider provider)
{
throw new InvalidCastException("Temperature to DateTime conversion is not supported.");
}
public decimal ToDecimal(IFormatProvider provider)
{
return this.m_Temp;
}
public double ToDouble(IFormatProvider provider)
{
return Decimal.ToDouble(this.m_Temp);
}
public short ToInt16(IFormatProvider provider)
{
if (this.m_Temp < Int16.MinValue || this.m_Temp > Int16.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the Int16 type.",
this.m_Temp));
else
return Decimal.ToInt16(this.m_Temp);
}
public int ToInt32(IFormatProvider provider)
{
if (this.m_Temp < Int32.MinValue || this.m_Temp > Int32.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the Int32 type.",
this.m_Temp));
else
return Decimal.ToInt32(this.m_Temp);
}
public long ToInt64(IFormatProvider provider)
{
if (this.m_Temp < Int64.MinValue || this.m_Temp > Int64.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the Int64 type.",
this.m_Temp));
else
return Decimal.ToInt64(this.m_Temp);
}
public sbyte ToSByte(IFormatProvider provider)
{
if (this.m_Temp < SByte.MinValue || this.m_Temp > SByte.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the SByte type.",
this.m_Temp));
else
return Decimal.ToSByte(this.m_Temp);
}
public float ToSingle(IFormatProvider provider)
{
return Decimal.ToSingle(this.m_Temp);
}
public string ToString(IFormatProvider provider)
{
return m_Temp.ToString("N2", provider) + "°C";
}
public object ToType(Type conversionType, IFormatProvider provider)
{
switch (Type.GetTypeCode(conversionType))
{
case TypeCode.Boolean:
return this.ToBoolean(null);
case TypeCode.Byte:
return this.ToByte(null);
case TypeCode.Char:
return this.ToChar(null);
case TypeCode.DateTime:
return this.ToDateTime(null);
case TypeCode.Decimal:
return this.ToDecimal(null);
case TypeCode.Double:
return this.ToDouble(null);
case TypeCode.Int16:
return this.ToInt16(null);
case TypeCode.Int32:
return this.ToInt32(null);
case TypeCode.Int64:
return this.ToInt64(null);
case TypeCode.Object:
if (typeof(Temperature).Equals(conversionType))
return this;
else
throw new InvalidCastException(String.Format("Conversion to a {0} is not supported.",
conversionType.Name));
case TypeCode.SByte:
return this.ToSByte(null);
case TypeCode.Single:
return this.ToSingle(null);
case TypeCode.String:
return this.ToString(provider);
case TypeCode.UInt16:
return this.ToUInt16(null);
case TypeCode.UInt32:
return this.ToUInt32(null);
case TypeCode.UInt64:
return this.ToUInt64(null);
default:
throw new InvalidCastException(String.Format("Conversion to {0} is not supported.", conversionType.Name));
}
}
public ushort ToUInt16(IFormatProvider provider)
{
if (this.m_Temp < UInt16.MinValue || this.m_Temp > UInt16.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the UInt16 type.",
this.m_Temp));
else
return Decimal.ToUInt16(this.m_Temp);
}
public uint ToUInt32(IFormatProvider provider)
{
if (this.m_Temp < UInt32.MinValue || this.m_Temp > UInt32.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the UInt32 type.",
this.m_Temp));
else
return Decimal.ToUInt32(this.m_Temp);
}
public ulong ToUInt64(IFormatProvider provider)
{
if (this.m_Temp < UInt64.MinValue || this.m_Temp > UInt64.MaxValue)
throw new OverflowException(String.Format("{0} is out of range of the UInt64 type.",
this.m_Temp));
else
return Decimal.ToUInt64(this.m_Temp);
}
}
Imports System.Globalization
Public Class Temperature : Implements IConvertible
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 m_Temp.ToString("N2") & "°C"
End Function
' IConvertible implementations.
Public Function GetTypeCode() As TypeCode _
Implements IConvertible.GetTypeCode
Return TypeCode.Object
End Function
Public Function ToBoolean(provider As IFormatProvider) As Boolean _
Implements IConvertible.ToBoolean
If m_Temp = 0 Then
Return False
Else
Return True
End If
End Function
Public Function ToByte(provider As IFormatProvider) As Byte _
Implements IConvertible.ToByte
If m_Temp < Byte.MinValue Or m_Temp > Byte.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the Byte type.", _
Me.m_Temp))
Else
Return Decimal.ToByte(Me.m_Temp)
End If
End Function
Public Function ToChar(provider As IFormatProvider) As Char _
Implements IConvertible.ToChar
Throw New InvalidCastException("Temperature to Char conversion is not supported.")
End Function
Public Function ToDateTime(provider As IFormatProvider) As Date _
Implements IConvertible.ToDateTime
Throw New InvalidCastException("Temperature to DateTime conversion is not supported.")
End Function
Public Function ToDecimal(provider As IFormatProvider) As Decimal _
Implements IConvertible.ToDecimal
Return Me.m_Temp
End Function
Public Function ToDouble(provider As IFormatProvider) As Double _
Implements IConvertible.ToDouble
Return Decimal.ToDouble(Me.m_Temp)
End Function
Public Function ToInt16(provider As IFormatProvider) As Int16 _
Implements IConvertible.ToInt16
If Me.m_Temp < Int16.MinValue Or Me.m_Temp > Int16.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the Int16 type.", _
Me.m_Temp))
Else
Return Decimal.ToInt16(Me.m_Temp)
End If
End Function
Public Function ToInt32(provider As IFormatProvider) As Int32 _
Implements IConvertible.ToInt32
If Me.m_Temp < Int32.MinValue Or Me.m_Temp > Int32.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the Int32 type.", _
Me.m_Temp))
Else
Return Decimal.ToInt32(Me.m_Temp)
End If
End Function
Public Function ToInt64(provider As IFormatProvider) As Int64 _
Implements IConvertible.ToInt64
If Me.m_Temp < Int64.MinValue Or Me.m_Temp > Int64.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the Int64 type.", _
Me.m_Temp))
Else
Return Decimal.ToInt64(Me.m_Temp)
End If
End Function
Public Function ToSByte(provider As IFormatProvider) As SByte _
Implements IConvertible.ToSByte
If Me.m_Temp < SByte.MinValue Or Me.m_Temp > SByte.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the SByte type.", _
Me.m_Temp))
Else
Return Decimal.ToSByte(Me.m_Temp)
End If
End Function
Public Function ToSingle(provider As IFormatProvider) As Single _
Implements IConvertible.ToSingle
Return Decimal.ToSingle(Me.m_Temp)
End Function
Public Overloads Function ToString(provider As IFormatProvider) As String _
Implements IConvertible.ToString
Return m_Temp.ToString("N2", provider) & "°C"
End Function
Public Function ToType(conversionType As Type, provider As IFormatProvider) As Object _
Implements IConvertible.ToType
Select Case Type.GetTypeCode(conversionType)
Case TypeCode.Boolean
Return Me.ToBoolean(Nothing)
Case TypeCode.Byte
Return Me.ToByte(Nothing)
Case TypeCode.Char
Return Me.ToChar(Nothing)
Case TypeCode.DateTime
Return Me.ToDateTime(Nothing)
Case TypeCode.Decimal
Return Me.ToDecimal(Nothing)
Case TypeCode.Double
Return Me.ToDouble(Nothing)
Case TypeCode.Int16
Return Me.ToInt16(Nothing)
Case TypeCode.Int32
Return Me.ToInt32(Nothing)
Case TypeCode.Int64
Return Me.ToInt64(Nothing)
Case TypeCode.Object
If GetType(Temperature).Equals(conversionType) Then
Return Me
Else
Throw New InvalidCastException(String.Format("Conversion to a {0} is not supported.", _
conversionType.Name))
End If
Case TypeCode.SByte
Return Me.ToSByte(Nothing)
Case TypeCode.Single
Return Me.ToSingle(Nothing)
Case TypeCode.String
Return Me.ToString(provider)
Case TypeCode.UInt16
Return Me.ToUInt16(Nothing)
Case TypeCode.UInt32
Return Me.ToUInt32(Nothing)
Case TypeCode.UInt64
Return Me.ToUInt64(Nothing)
Case Else
Throw New InvalidCastException(String.Format("Conversion to {0} is not supported.", conversionType.Name))
End Select
End Function
Public Function ToUInt16(provider As IFormatProvider) As UInt16 _
Implements IConvertible.ToUInt16
If Me.m_Temp < UInt16.MinValue Or Me.m_Temp > UInt16.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the UInt16 type.", _
Me.m_Temp))
Else
Return Decimal.ToUInt16(Me.m_Temp)
End If
End Function
Public Function ToUInt32(provider As IFormatProvider) As UInt32 _
Implements IConvertible.ToUInt32
If Me.m_Temp < UInt32.MinValue Or Me.m_Temp > UInt32.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the UInt32 type.", _
Me.m_Temp))
Else
Return Decimal.ToUInt32(Me.m_Temp)
End If
End Function
Public Function ToUInt64(provider As IFormatProvider) As UInt64 _
Implements IConvertible.ToUInt64
If Me.m_Temp < UInt64.MinValue Or Me.m_Temp > UInt64.MaxValue Then
Throw New OverflowException(String.Format("{0} is out of range of the UInt64 type.", _
Me.m_Temp))
Else
Return Decimal.ToUInt64(Me.m_temp)
End If
End Function
End Class
Im folgenden Beispiel wird eine Instanz der Temperature
-Klasse erstellt und die- ChangeType(Object, Type, IFormatProvider) Methode aufgerufen, um Sie in die grundlegenden numerischen Typen zu konvertieren, die von .net und in unterstützt werden String .The following example creates an instance of the Temperature
class and calls the ChangeType(Object, Type, IFormatProvider) method to convert it to the basic numeric types supported by .NET and to a String. Es veranschaulicht, dass die ChangeType -Methode einen Rückruf für die-Implementierung des Quell Typs umschließt IConvertible .It illustrates that the ChangeType method wraps a call to the source type's IConvertible implementation.
void main()
{
Temperature^ cool = gcnew Temperature(5);
array<Type^>^ targetTypes = gcnew array<Type^> { SByte::typeid, Int16::typeid, Int32::typeid,
Int64::typeid, Byte::typeid, UInt16::typeid,
UInt32::typeid, UInt64::typeid, Decimal::typeid,
Single::typeid, Double::typeid, String::typeid };
CultureInfo^ provider = gcnew CultureInfo("fr-FR");
for each (Type^ targetType in targetTypes)
{
try {
Object^ value = Convert::ChangeType(cool, targetType, provider);
Console::WriteLine("Converted {0} {1} to {2} {3}.",
cool->GetType()->Name, cool->ToString(),
targetType->Name, value);
}
catch (InvalidCastException^) {
Console::WriteLine("Unsupported {0} --> {1} conversion.",
cool->GetType()->Name, targetType->Name);
}
catch (OverflowException^) {
Console::WriteLine("{0} is out of range of the {1} type.",
cool, targetType->Name);
}
}
}
// The example dosplays the following output:
// Converted Temperature 5.00�C to SByte 5.
// Converted Temperature 5.00�C to Int16 5.
// Converted Temperature 5.00�C to Int32 5.
// Converted Temperature 5.00�C to Int64 5.
// Converted Temperature 5.00�C to Byte 5.
// Converted Temperature 5.00�C to UInt16 5.
// Converted Temperature 5.00�C to UInt32 5.
// Converted Temperature 5.00�C to UInt64 5.
// Converted Temperature 5.00�C to Decimal 5.
// Converted Temperature 5.00�C to Single 5.
// Converted Temperature 5.00�C to Double 5.
// Converted Temperature 5.00�C to String 5,00�C.
public class Example
{
public static void Main()
{
Temperature cool = new Temperature(5);
Type[] targetTypes = { typeof(SByte), typeof(Int16), typeof(Int32),
typeof(Int64), typeof(Byte), typeof(UInt16),
typeof(UInt32), typeof(UInt64), typeof(Decimal),
typeof(Single), typeof(Double), typeof(String) };
CultureInfo provider = new CultureInfo("fr-FR");
foreach (Type targetType in targetTypes)
{
try {
object value = Convert.ChangeType(cool, targetType, provider);
Console.WriteLine("Converted {0} {1} to {2} {3}.",
cool.GetType().Name, cool.ToString(),
targetType.Name, value);
}
catch (InvalidCastException) {
Console.WriteLine("Unsupported {0} --> {1} conversion.",
cool.GetType().Name, targetType.Name);
}
catch (OverflowException) {
Console.WriteLine("{0} is out of range of the {1} type.",
cool, targetType.Name);
}
}
}
}
// The example dosplays the following output:
// Converted Temperature 5.00°C to SByte 5.
// Converted Temperature 5.00°C to Int16 5.
// Converted Temperature 5.00°C to Int32 5.
// Converted Temperature 5.00°C to Int64 5.
// Converted Temperature 5.00°C to Byte 5.
// Converted Temperature 5.00°C to UInt16 5.
// Converted Temperature 5.00°C to UInt32 5.
// Converted Temperature 5.00°C to UInt64 5.
// Converted Temperature 5.00°C to Decimal 5.
// Converted Temperature 5.00°C to Single 5.
// Converted Temperature 5.00°C to Double 5.
// Converted Temperature 5.00°C to String 5,00°C.
Module Example
Public Sub Main()
Dim cool As New Temperature(5)
Dim targetTypes() As Type = { GetType(SByte), GetType(Int16), GetType(Int32), _
GetType(Int64), GetType(Byte), GetType(UInt16), _
GetType(UInt32), GetType(UInt64), GetType(Decimal), _
GetType(Single), GetType(Double), GetType(String) }
Dim provider As New CultureInfo("fr-FR")
For Each targetType As Type In targetTypes
Try
Dim value As Object = Convert.ChangeType(cool, targetType, provider)
Console.WriteLine("Converted {0} {1} to {2} {3}.", _
cool.GetType().Name, cool.ToString(), _
targetType.Name, value)
Catch e As InvalidCastException
Console.WriteLine("Unsupported {0} --> {1} conversion.", _
cool.GetType().Name, targetType.Name)
Catch e As OverflowException
Console.WriteLine("{0} is out of range of the {1} type.", _
cool, targetType.Name)
End Try
Next
End Sub
End Module
' The example displays the following output:
' Converted Temperature 5.00°C to SByte 5.
' Converted Temperature 5.00°C to Int16 5.
' Converted Temperature 5.00°C to Int32 5.
' Converted Temperature 5.00°C to Int64 5.
' Converted Temperature 5.00°C to Byte 5.
' Converted Temperature 5.00°C to UInt16 5.
' Converted Temperature 5.00°C to UInt32 5.
' Converted Temperature 5.00°C to UInt64 5.
' Converted Temperature 5.00°C to Decimal 5.
' Converted Temperature 5.00°C to Single 5.
' Converted Temperature 5.00°C to Double 5.
' Converted Temperature 5.00°C to String 5,00°C.
Hinweise
ChangeType ist eine allgemeine Konvertierungsmethode, die das von angegebene Objekt value
in konvertiert conversionType
.ChangeType is a general-purpose conversion method that converts the object specified by value
to conversionType
. Der value
-Parameter kann ein Objekt eines beliebigen Typs sein, und es conversionType
kann sich auch um ein-Objekt handeln, das einen Type beliebigen Basis-oder benutzerdefinierten Typ darstellt.The value
parameter can be an object of any type, and conversionType
can also be a Type object that represents any base or custom type. Damit die Konvertierung erfolgreich durchgeführt werden kann, value
muss die- IConvertible Schnittstelle implementieren, da die-Methode einfach einen aufzurufenden-Methode umschließt IConvertible .For the conversion to succeed, value
must implement the IConvertible interface, because the method simply wraps a call to an appropriate IConvertible method. Die-Methode erfordert, dass die Konvertierung von value
in conversionType
unterstützt wird.The method requires that conversion of value
to conversionType
be supported.
Der- provider
Parameter ist eine- IFormatProvider Implementierung, die Formatierungsinformationen für die Konvertierung bereitstellt.The provider
parameter is an IFormatProvider implementation that supplies formatting information for the conversion. Ob und wie dieser Parameter verwendet wird, hängt von der zugrunde liegenden IConvertible Implementierung ab.Whether and how this parameter is used depends on the underlying IConvertible implementation. Wenn value
ein Basis Datentyp ist, provider
wird nur für die folgenden Konvertierungen verwendet:If value
is a base data type, provider
is used only for the following conversions:
Konvertierung von einer Zahl in eine Zeichenfolge oder von einer Zeichenfolge in eine Zahl.Conversion from a number to a string, or from a string to a number.
provider
muss ein- CultureInfo Objekt, ein- NumberFormatInfo Objekt oder eine benutzerdefinierte-Implementierung sein, IFormatProvider die ein-Objekt zurückgibt NumberFormatInfo .provider
must be a CultureInfo object, a NumberFormatInfo object, or a custom IFormatProvider implementation that returns a NumberFormatInfo object. Da die- ChangeType(Object, TypeCode, IFormatProvider) Methode die Konvertierung jedoch mit dem Standardformat Bezeichner "G" ausführt, hat der-provider
Parameter keine Auswirkung, wennvalue
oder der Zieltyp eine Ganzzahl ohne Vorzeichen ist.However, because the ChangeType(Object, TypeCode, IFormatProvider) method performs the conversion using the default "G" format specifier, theprovider
parameter has no effect ifvalue
or the target type is an unsigned integer. Wennprovider
istnull
, CultureInfo wird das Objekt verwendet, das die aktuelle Thread Kultur darstellt.Ifprovider
isnull
, the CultureInfo object that represents the current thread culture is used.Konvertierung von einem DateTime Wert in eine Zeichenfolge oder von einer Zeichenfolge in einen- DateTime Wert.Conversion from a DateTime value to a string, or from a string to a DateTime value.
provider
muss ein- CultureInfo oder- DateTimeFormatInfo Objekt sein.provider
must be a CultureInfo or DateTimeFormatInfo object. Wennprovider
istnull
, CultureInfo wird das Objekt verwendet, das die aktuelle Thread Kultur darstellt.Ifprovider
isnull
, the CultureInfo object that represents the current thread culture is used.
Wenn value
ein Anwendungs definierter Typ ist, IConvertible kann die Implementierung den- provider
Parameter verwenden.If value
is an application-defined type, its IConvertible implementation may use the provider
parameter.
Hinweise für Aufrufer
Die- ChangeType(Object, Type, IFormatProvider) Methode kann einen Enumerationswert in einen anderen Typ konvertieren.The ChangeType(Object, Type, IFormatProvider) method can convert an enumeration value to another type. Es ist jedoch nicht möglich, einen anderen Typ in einen Enumerationswert zu konvertieren, auch wenn der Quelltyp der zugrunde liegende Typ der Enumeration ist.However, it cannot convert another type to an enumeration value, even if the source type is the underlying type of the enumeration. Verwenden Sie zum Konvertieren eines Typs in einen Enumerationswert einen Typumwandlungs Operator (in c#) oder eine Konvertierungs Funktion (in Visual Basic).To convert a type to an enumeration value, use a casting operator (in C#) or a conversion function (in Visual Basic). Das folgende Beispiel veranschaulicht die Konvertierung in einen und aus einem Kontinent
-Enumerationswert.The following example illustrates the conversion to and from a Continent
enumeration value.
::: Code language = "CSharp" Source = "~/Samples/Snippets/CSharp/VS_Snippets_CLR_System/System.Convert.ChangeType/CS/changetype_enum2. cs" Interactive = "try-dotnet" ID = "Snippet5":::::: Code language = "vb" Source = "~/Samples/Snippets/VisualBasic/VS_Snippets_CLR_System/System.Convert.ChangeType/VB/changetype_enum2. vb" ID = "Snippet5"::::::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR_System/system.convert.changetype/cs/changetype_enum2.cs" interactive="try-dotnet" id="Snippet5"::: :::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.convert.changetype/vb/changetype_enum2.vb" id="Snippet5":::
Die ChangeType(Object, Type, IFormatProvider) Methode kann einen Typ, der NULL-Werte zulässt, in einen anderen Typ konvertieren.The ChangeType(Object, Type, IFormatProvider) method can convert a nullable type to another type. Es ist jedoch nicht möglich, einen anderen Typ in einen Wert eines Typs zu konvertieren, der NULL-Werte zulässt, auch wenn conversionType
der zugrunde liegende Typ von ist Nullable<T> .However, it cannot convert another type to a value of a nullable type, even if conversionType
is the underlying type of the Nullable<T>. Sie können einen Typumwandlungs Operator (in c#) oder eine Konvertierungs Funktion (in Visual Basic) verwenden, um die Konvertierung auszuführen.To perform the conversion, you can use a casting operator (in C#) or a conversion function (in Visual Basic). Im folgenden Beispiel wird die Konvertierung in einen und aus einem Werte zulässt-Typ veranschaulicht.The following example illustrates the conversion to and from a nullable type.
::: Code language = "CSharp" Source = "~/Samples/Snippets/CSharp/VS_Snippets_CLR_System/System.Convert.ChangeType/CS/changetype_nullable_1. cs" Interactive = "try-dotnet" ID = "Snippet8":::::: Code language = "vb" Source = "~/Samples/Snippets/VisualBasic/VS_Snippets_CLR_System/System.Convert.ChangeType/VB/changetype_nullable_1. vb" ID = "Snippet8"::::::code language="csharp" source="~/samples/snippets/csharp/VS_Snippets_CLR_System/system.convert.changetype/cs/changetype_nullable_1.cs" interactive="try-dotnet" id="Snippet8"::: :::code language="vb" source="~/samples/snippets/visualbasic/VS_Snippets_CLR_System/system.convert.changetype/vb/changetype_nullable_1.vb" id="Snippet8":::
Gilt für:
ChangeType(Object, TypeCode, IFormatProvider)
Gibt ein Objekt vom angegebenen Typ zurück, dessen Wert dem angegebenen Objekt entspricht.Returns an object of the specified type whose value is equivalent to the specified object. Ein Parameter liefert kulturspezifische Formatierungsinformationen.A parameter supplies culture-specific formatting information.
public:
static System::Object ^ ChangeType(System::Object ^ value, TypeCode typeCode, IFormatProvider ^ provider);
public static object ChangeType (object value, TypeCode typeCode, IFormatProvider provider);
public static object? ChangeType (object? value, TypeCode typeCode, IFormatProvider? provider);
static member ChangeType : obj * TypeCode * IFormatProvider -> obj
Public Shared Function ChangeType (value As Object, typeCode As TypeCode, provider As IFormatProvider) As Object
Parameter
- value
- Object
Ein Objekt, das die IConvertible-Schnittstelle implementiert.An object that implements the IConvertible interface.
- typeCode
- TypeCode
Der Typ des zurückzugebenden Objekts.The type of object to return.
- provider
- IFormatProvider
Ein Objekt, das kulturspezifische Formatierungsinformationen bereitstellt.An object that supplies culture-specific formatting information.
Gibt zurück
Ein Objekt, dem typeCode
als Typ zugrunde liegt und dessen Wert value
entspricht.An object whose underlying type is typeCode
and whose value is equivalent to value
.
- oder --or-
Ein Nullverweis (Nothing
in Visual Basic), wenn value
null
ist und typeCode
Empty, String oder Object ist.A null reference (Nothing
in Visual Basic), if value
is null
and typeCode
is Empty, String, or Object.
Ausnahmen
Diese Konvertierung wird nicht unterstützt.This conversion is not supported.
- oder --or-
value
ist null
, und typeCode
gibt einen Werttyp an.value
is null
and typeCode
specifies a value type.
- oder --or-
Die IConvertible-Schnittstelle wird von value
nicht implementiert.value
does not implement the IConvertible interface.
value
weist kein Format für den typeCode
-Typ auf, der von provider
erkannt wird.value
is not in a format for the typeCode
type recognized by provider
.
value
stellt eine Zahl außerhalb des Bereichs des typeCode
-Typs dar.value
represents a number that is out of the range of the typeCode
type.
typeCode
ist ungültig.typeCode
is invalid.
Beispiele
Im folgenden Beispiel wird ein benutzerdefinierter Format Anbieter mit dem Namen definiert InterceptProvider
, der angibt, wann seine- GetFormat Methode aufgerufen wird, und einen NumberFormatInfo für die fr-FR-Kultur und ein DateTimeFormatInfo -Objekt für die Kultur en-US zurückgibt.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. Dieser Format Anbieter wird bei allen Aufrufen der- ChangeType(Object, TypeCode, IFormatProvider) Methode verwendet.This format provider is used in all calls to the ChangeType(Object, TypeCode, IFormatProvider) method. Im Beispiel wird dann ein Array mit einem Double -Wert und einem- DateTime Wert erstellt, und es werden wiederholte Aufrufe ChangeType(Object, TypeCode, IFormatProvider) von mit jedem Wert und jedem Member der- TypeCode Enumeration durchführt.The example then creates an array with a Double and a DateTime value and makes repeated calls to ChangeType(Object, TypeCode, IFormatProvider) with each value and each member of the TypeCode enumeration. Das Beispiel veranschaulicht, wann die-Methode den IFormatProvider -Parameter verwendet, und veranschaulicht die Verwendung des- provider
Parameters, um die Kultur abhängige Formatierung auszuführen.The example illustrates when the method uses the IFormatProvider parameter and also illustrates the use of the provider
parameter to perform culture-sensitive formatting.
using namespace System;
using namespace System::Globalization;
ref class InterceptProvider : IFormatProvider
{
public:
virtual Object^ GetFormat(Type^ formatType)
{
CultureInfo^ culture;
if (formatType == NumberFormatInfo::typeid) {
Console::WriteLine(" Returning a fr-FR numeric format provider.");
culture = gcnew CultureInfo("fr-FR");
return culture->NumberFormat;
}
else if (formatType == DateTimeFormatInfo::typeid) {
Console::WriteLine(" Returning an en-US date/time format provider.");
culture = gcnew CultureInfo("en-US");
return culture->DateTimeFormat;
}
else {
Console::WriteLine(" Requesting a format provider of {0}.", formatType->Name);
return nullptr;
}
}
};
void main()
{
array<Object^>^ values = gcnew array<Object^> { 103.5, gcnew DateTime(2010, 12, 26, 14, 34, 0) };
IFormatProvider^ provider = gcnew InterceptProvider();
// Convert value to each of the types represented in TypeCode enum.
for each (Object^ value in values)
{
// Iterate types in TypeCode enum.
for each (TypeCode enumType in (array<TypeCode>^) Enum::GetValues(TypeCode::typeid))
{
if (enumType == TypeCode::DBNull || enumType == TypeCode::Empty) continue;
try {
Console::WriteLine("{0} ({1}) --> {2} ({3}).",
value, value->GetType()->Name,
Convert::ChangeType(value, enumType, provider),
enumType.ToString());
}
catch (InvalidCastException^ e) {
Console::WriteLine("Cannot convert a {0} to a {1}",
value->GetType()->Name, enumType.ToString());
}
catch (OverflowException^ e) {
Console::WriteLine("Overflow: {0} is out of the range of a {1}",
value, enumType.ToString());
}
}
Console::WriteLine();
}
}
// The example displays the following output:
// 103.5 (Double) --> 103.5 (Object).
// 103.5 (Double) --> True (Boolean).
// Cannot convert a Double to a Char
// 103.5 (Double) --> 104 (SByte).
// 103.5 (Double) --> 104 (Byte).
// 103.5 (Double) --> 104 (Int16).
// 103.5 (Double) --> 104 (UInt16).
// 103.5 (Double) --> 104 (Int32).
// 103.5 (Double) --> 104 (UInt32).
// 103.5 (Double) --> 104 (Int64).
// 103.5 (Double) --> 104 (UInt64).
// 103.5 (Double) --> 103.5 (Single).
// 103.5 (Double) --> 103.5 (Double).
// 103.5 (Double) --> 103.5 (Decimal).
// Cannot convert a Double to a DateTime
// Returning a fr-FR numeric format provider.
// 103.5 (Double) --> 103,5 (String).
//
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (Object).
// Cannot convert a DateTime to a Boolean
// Cannot convert a DateTime to a Char
// Cannot convert a DateTime to a SByte
// Cannot convert a DateTime to a Byte
// Cannot convert a DateTime to a Int16
// Cannot convert a DateTime to a UInt16
// Cannot convert a DateTime to a Int32
// Cannot convert a DateTime to a UInt32
// Cannot convert a DateTime to a Int64
// Cannot convert a DateTime to a UInt64
// Cannot convert a DateTime to a Single
// Cannot convert a DateTime to a Double
// Cannot convert a DateTime to a Decimal
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (DateTime).
// Returning an en-US date/time format provider.
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (String).
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();
// Convert value to each of the types represented in TypeCode enum.
foreach (object value in values)
{
// Iterate types in TypeCode enum.
foreach (TypeCode enumType in ((TypeCode[]) Enum.GetValues(typeof(TypeCode))))
{
if (enumType == TypeCode.DBNull || enumType == TypeCode.Empty) continue;
try {
Console.WriteLine("{0} ({1}) --> {2} ({3}).",
value, value.GetType().Name,
Convert.ChangeType(value, enumType, provider),
enumType.ToString());
}
catch (InvalidCastException) {
Console.WriteLine("Cannot convert a {0} to a {1}",
value.GetType().Name, enumType.ToString());
}
catch (OverflowException) {
Console.WriteLine("Overflow: {0} is out of the range of a {1}",
value, enumType.ToString());
}
}
Console.WriteLine();
}
}
}
// The example displays the following output:
// 103.5 (Double) --> 103.5 (Object).
// 103.5 (Double) --> True (Boolean).
// Cannot convert a Double to a Char
// 103.5 (Double) --> 104 (SByte).
// 103.5 (Double) --> 104 (Byte).
// 103.5 (Double) --> 104 (Int16).
// 103.5 (Double) --> 104 (UInt16).
// 103.5 (Double) --> 104 (Int32).
// 103.5 (Double) --> 104 (UInt32).
// 103.5 (Double) --> 104 (Int64).
// 103.5 (Double) --> 104 (UInt64).
// 103.5 (Double) --> 103.5 (Single).
// 103.5 (Double) --> 103.5 (Double).
// 103.5 (Double) --> 103.5 (Decimal).
// Cannot convert a Double to a DateTime
// Returning a fr-FR numeric format provider.
// 103.5 (Double) --> 103,5 (String).
//
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (Object).
// Cannot convert a DateTime to a Boolean
// Cannot convert a DateTime to a Char
// Cannot convert a DateTime to a SByte
// Cannot convert a DateTime to a Byte
// Cannot convert a DateTime to a Int16
// Cannot convert a DateTime to a UInt16
// Cannot convert a DateTime to a Int32
// Cannot convert a DateTime to a UInt32
// Cannot convert a DateTime to a Int64
// Cannot convert a DateTime to a UInt64
// Cannot convert a DateTime to a Single
// Cannot convert a DateTime to a Double
// Cannot convert a DateTime to a Decimal
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (DateTime).
// Returning an en-US date/time format provider.
// 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (String).
Imports System.Globalization
Public Class InterceptProvider : Implements IFormatProvider
Public Function GetFormat(formatType As Type) As Object _
Implements IFormatProvider.GetFormat
If formatType.Equals(GetType(NumberFormatInfo)) Then
Console.WriteLine(" Returning a fr-FR numeric format provider.")
Return New CultureInfo("fr-FR").NumberFormat
ElseIf formatType.Equals(GetType(DateTimeFormatInfo)) Then
Console.WriteLine(" Returning an en-US date/time format provider.")
Return New CultureInfo("en-US").DateTimeFormat
Else
Console.WriteLine(" Requesting a format provider of {0}.", formatType.Name)
Return Nothing
End If
End Function
End Class
Module Example
Public Sub Main()
Dim values() As Object = { 103.5r, #12/26/2010 2:34PM# }
Dim provider As New InterceptProvider()
' Convert value to each of the types represented in TypeCode enum.
For Each value As Object In values
' Iterate types in TypeCode enum.
For Each enumType As TypeCode In DirectCast([Enum].GetValues(GetType(TypeCode)), TypeCode())
If enumType = TypeCode.DbNull Or enumType = TypeCode.Empty Then Continue For
Try
Console.WriteLine("{0} ({1}) --> {2} ({3}).", _
value, value.GetType().Name, _
Convert.ChangeType(value, enumType, provider), _
enumType.ToString())
Catch e As InvalidCastException
Console.WriteLine("Cannot convert a {0} to a {1}", _
value.GetType().Name, enumType.ToString())
Catch e As OverflowException
Console.WriteLine("Overflow: {0} is out of the range of a {1}", _
value, enumType.ToString())
End Try
Next
Console.WriteLine()
Next
End Sub
End Module
' The example displays the following output:
' 103.5 (Double) --> 103.5 (Object).
' 103.5 (Double) --> True (Boolean).
' Cannot convert a Double to a Char
' 103.5 (Double) --> 104 (SByte).
' 103.5 (Double) --> 104 (Byte).
' 103.5 (Double) --> 104 (Int16).
' 103.5 (Double) --> 104 (UInt16).
' 103.5 (Double) --> 104 (Int32).
' 103.5 (Double) --> 104 (UInt32).
' 103.5 (Double) --> 104 (Int64).
' 103.5 (Double) --> 104 (UInt64).
' 103.5 (Double) --> 103.5 (Single).
' 103.5 (Double) --> 103.5 (Double).
' 103.5 (Double) --> 103.5 (Decimal).
' Cannot convert a Double to a DateTime
' Returning a fr-FR numeric format provider.
' 103.5 (Double) --> 103,5 (String).
'
' 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (Object).
' Cannot convert a DateTime to a Boolean
' Cannot convert a DateTime to a Char
' Cannot convert a DateTime to a SByte
' Cannot convert a DateTime to a Byte
' Cannot convert a DateTime to a Int16
' Cannot convert a DateTime to a UInt16
' Cannot convert a DateTime to a Int32
' Cannot convert a DateTime to a UInt32
' Cannot convert a DateTime to a Int64
' Cannot convert a DateTime to a UInt64
' Cannot convert a DateTime to a Single
' Cannot convert a DateTime to a Double
' Cannot convert a DateTime to a Decimal
' 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (DateTime).
' Returning an en-US date/time format provider.
' 12/26/2010 2:34:00 PM (DateTime) --> 12/26/2010 2:34:00 PM (String).
Hinweise
ChangeType(Object, TypeCode, IFormatProvider) ist eine allgemeine Konvertierungsmethode, die das durch angegebene Objekt value
in einen vordefinierten Typ konvertiert, der durch angegeben wird typeCode
.ChangeType(Object, TypeCode, IFormatProvider) is a general-purpose conversion method that converts the object specified by value
to a predefined type specified by typeCode
. Der- value
Parameter kann ein Objekt eines beliebigen Typs sein.The value
parameter can be an object of any type. Damit die Konvertierung erfolgreich durchgeführt werden kann, value
muss die- IConvertible Schnittstelle implementieren, da die-Methode einfach einen aufzurufenden-Methode umschließt IConvertible .For the conversion to succeed, value
must implement the IConvertible interface, because the method simply wraps a call to an appropriate IConvertible method. Die-Methode erfordert auch, dass die Konvertierung von value
in typeCode
unterstützt wird.The method also requires that conversion of value
to typeCode
be supported.
Die- ChangeType(Object, TypeCode, IFormatProvider) Methode unterstützt nicht die Konvertierung von value
in einen benutzerdefinierten Typ.The ChangeType(Object, TypeCode, IFormatProvider) method does not support the conversion of value
to a custom type. Um eine solche Konvertierung auszuführen, wird die- ChangeType(Object, Type, IFormatProvider) Methode aufgerufen.To perform such a conversion, call the ChangeType(Object, Type, IFormatProvider) method.
Der- provider
Parameter ist eine- IFormatProvider Implementierung, die Formatierungsinformationen für die Konvertierung bereitstellt.The provider
parameter is an IFormatProvider implementation that supplies formatting information for the conversion. Ob und wie dieser Parameter verwendet wird, hängt von der zugrunde liegenden IConvertible Implementierung ab.Whether and how this parameter is used depends on the underlying IConvertible implementation. Wenn value
ein Basis Datentyp ist, provider
wird nur für die folgenden Konvertierungen verwendet.If value
is a base data type, provider
is used only for the following conversions. Wenn ein- null
IFormatProvider Argument an diese Methoden übermittelt wird, wird das- CultureInfo Objekt verwendet, das die aktuelle Thread Kultur darstellt.If a null
IFormatProvider argument is passed to these methods, the CultureInfo object that represents the current thread culture is used.
Konvertierung von einer Zahl in eine Zeichenfolge oder von einer Zeichenfolge in eine Zahl.Conversion from a number to a string, or from a string to a number.
provider
muss ein- CultureInfo Objekt, ein- NumberFormatInfo Objekt oder eine benutzerdefinierte-Implementierung sein, IFormatProvider die ein-Objekt zurückgibt NumberFormatInfo .provider
must be a CultureInfo object, a NumberFormatInfo object, or a custom IFormatProvider implementation that returns a NumberFormatInfo object. Da die- ChangeType(Object, TypeCode, IFormatProvider) Methode die Konvertierung jedoch mit dem Standardformat Bezeichner "G" ausführt, hat der-provider
Parameter keine Auswirkung, wennvalue
oder der Zieltyp eine Ganzzahl ohne Vorzeichen ist.However, because the ChangeType(Object, TypeCode, IFormatProvider) method performs the conversion using the default "G" format specifier, theprovider
parameter has no effect ifvalue
or the target type is an unsigned integer.Konvertierung von einem DateTime Wert in eine Zeichenfolge oder von einer Zeichenfolge in einen- DateTime Wert.Conversion from a DateTime value to a string, or from a string to a DateTime value.
provider
muss ein- CultureInfo oder- DateTimeFormatInfo Objekt sein.provider
must be a CultureInfo or DateTimeFormatInfo object.
Wenn value
ein Anwendungs definierter Typ ist, IConvertible kann die Implementierung den- provider
Parameter verwenden.If value
is an application-defined type, its IConvertible implementation may use the provider
parameter.