Convert.ChangeType Metode
Definisi
Penting
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Mengembalikan objek dari jenis tertentu yang nilainya setara dengan objek tertentu.
Overload
ChangeType(Object, Type) |
Mengembalikan objek dari jenis yang ditentukan dan yang nilainya setara dengan objek yang ditentukan. |
ChangeType(Object, TypeCode) |
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan. |
ChangeType(Object, Type, IFormatProvider) |
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan. Parameter memasok informasi pemformatan khusus budaya. |
ChangeType(Object, TypeCode, IFormatProvider) |
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan. Parameter memasok informasi pemformatan khusus budaya. |
ChangeType(Object, Type)
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
Mengembalikan objek dari jenis yang ditentukan dan yang nilainya setara dengan objek yang ditentukan.
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
Objek yang mengimplementasikan antarmuka IConvertible.
- conversionType
- Type
Jenis objek yang akan dikembalikan.
Mengembalikan
Objek yang jenisnya conversionType
dan nilainya setara dengan value
.
-atau-
Referensi null (Nothing
di Visual Basic), jika value
null
dan conversionType
bukan jenis nilai.
Pengecualian
Konversi ini tidak didukung.
-atau-
value
null
dan conversionType
adalah jenis nilai.
-atau-
value
tidak mengimplementasikan antarmuka IConvertible.
value
tidak dalam format yang dikenali oleh conversionType
.
value
mewakili angka yang berada di luar rentang conversionType
.
conversionType
null
.
Contoh
Contoh berikut mengilustrasikan penggunaan metode ChangeType.
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);
}
}
open System
let d = -2.345
let i = Convert.ChangeType(d, typeof<int>) :?> int
printfn $"The double value {d} when converted to an int becomes {i}"
let s = "12/12/98"
let dt = Convert.ChangeType(s, typeof<DateTime>) :?> DateTime
printfn $"The string value {s} when converted to a Date becomes {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
Keterangan
ChangeType adalah metode konversi tujuan umum yang mengonversi objek yang ditentukan oleh value
menjadi conversionType
. Parameter value
dapat menjadi objek dari jenis apa pun, dan conversionType
juga dapat menjadi objek Type yang mewakili jenis dasar atau kustom apa pun. Agar konversi berhasil, value
harus menerapkan antarmuka IConvertible, karena metode ini hanya membungkus panggilan ke metode IConvertible yang sesuai. Metode ini mengharuskan konversi value
ke conversionType
didukung.
Metode ini menggunakan budaya utas saat ini untuk konversi.
Catatan Bagi Pemanggil
Metode ChangeType(Object, Type) dapat mengonversi nilai enumerasi ke jenis lain. Namun, itu tidak dapat mengonversi jenis lain ke nilai enumerasi, bahkan jika jenis sumber adalah jenis enumerasi yang mendasar. Untuk mengonversi jenis menjadi nilai enumerasi, gunakan operator transmisi (di C#) atau fungsi konversi (di Visual Basic). Contoh berikut mengilustrasikan konversi ke dan dari nilai enumerasi Continent
.
using System;
public enum Continent
{
Africa, Antarctica, Asia, Australia, Europe,
NorthAmerica, SouthAmerica
};
public class Example
{
public static void Main()
{
// Convert a Continent to a Double.
Continent cont = Continent.NorthAmerica;
Console.WriteLine("{0:N2}",
Convert.ChangeType(cont, typeof(Double)));
// Convert a Double to a Continent.
Double number = 6.0;
try {
Console.WriteLine("{0}",
Convert.ChangeType(number, typeof(Continent)));
}
catch (InvalidCastException) {
Console.WriteLine("Cannot convert a Double to a Continent");
}
Console.WriteLine("{0}", (Continent) number);
}
}
// The example displays the following output:
// 5.00
// Cannot convert a Double to a Continent
// SouthAmerica
open System
type Continent =
| Africa = 0
| Antarctica = 1
| Asia = 2
| Australia = 3
| Europe = 4
| NorthAmerica = 5
| SouthAmerica = 6
// Convert a Continent to a Double.
let cont = Continent.NorthAmerica
printfn $"{Convert.ChangeType(cont, typeof<Double>):N2}"
// Convert a Double to a Continent.
let number = 6.0
try
printfn $"{Convert.ChangeType(number, typeof<Continent>)}"
with :? InvalidCastException ->
printfn "Cannot convert a Double to a Continent"
printfn $"{int number |> enum<Continent>}"
// The example displays the following output:
// 5.00
// Cannot convert a Double to a Continent
// SouthAmerica
Public Enum Continent As Integer
Africa = 0
Antarctica = 1
Asia = 2
Australia = 3
Europe = 4
NorthAmerica = 5
SouthAmerica = 6
End Enum
Module Example
Public Sub Main()
' Convert a Continent to a Double.
Dim cont As Continent = Continent.NorthAmerica
Console.WriteLine("{0:N2}",
Convert.ChangeType(cont, GetType(Double)))
' Convert a Double to a Continent.
Dim number As Double = 6.0
Try
Console.WriteLine("{0}",
Convert.ChangeType(number, GetType(Continent)))
Catch e As InvalidCastException
Console.WriteLine("Cannot convert a Double to a Continent")
End Try
Console.WriteLine("{0}", CType(number, Continent))
End Sub
End Module
' The example displays the following output:
' 5.00
' Cannot convert a Double to a Continent
' SouthAmerica
Metode ChangeType(Object, Type) dapat mengonversi jenis nullable ke jenis lain. Namun, itu tidak dapat mengonversi jenis lain ke nilai jenis nullable, bahkan jika conversionType
adalah jenis yang mendasar dari Nullable<T>. Untuk melakukan konversi, Anda dapat menggunakan operator transmisi (di C#) atau fungsi konversi (di Visual Basic). Contoh berikut mengilustrasikan konversi ke dan dari jenis yang dapat diubah ke null.
using System;
public class Example
{
public static void Main()
{
int? intValue1 = 12893;
double dValue1 = (double) Convert.ChangeType(intValue1, typeof(Double));
Console.WriteLine("{0} ({1})--> {2} ({3})", intValue1, intValue1.GetType().Name,
dValue1, dValue1.GetType().Name);
float fValue1 = 16.3478f;
int? intValue2 = (int) fValue1;
Console.WriteLine("{0} ({1})--> {2} ({3})", fValue1, fValue1.GetType().Name,
intValue2, intValue2.GetType().Name);
}
}
// The example displays the following output:
// 12893 (Int32)--> 12893 (Double)
// 16.3478 (Single)--> 16 (Int32)
open System
let intValue1 = Nullable 12893
let dValue1 = Convert.ChangeType(intValue1, typeof<Double>) :?> double
printfn $"{intValue1} ({intValue1.GetType().Name})--> {dValue1} ({dValue1.GetType().Name})"
let fValue1 = 16.3478f
let intValue2 = Nullable(int fValue1)
printfn $"{fValue1} ({fValue1.GetType().Name})--> {intValue2} ({intValue2.GetType().Name})"
// The example displays the following output:
// 12893 (Int32)--> 12893 (Double)
// 16.3478 (Single)--> 16 (Int32)
Module Example
Public Sub Main()
Dim intValue1 As Integer? = 12893
Dim dValue1 As Double = CType(Convert.ChangeType(intValue1, GetType(Double)), Double)
Console.WriteLine("{0} ({1})--> {2} ({3})", intValue1, intValue1.GetType().Name,
dValue1, dValue1.GetType().Name)
Dim fValue1 As Single = 16.3478
Dim intValue2 As Integer? = CType(fValue1, Integer)
Console.WriteLine("{0} ({1})--> {2} ({3})", fValue1, fValue1.GetType().Name,
intValue2, intValue2.GetType().Name)
End Sub
End Module
' The example displays the following output:
' 12893 (Int32)--> 12893 (Double)
' 16.3478 (Single)--> 16 (Int32)
Berlaku untuk
ChangeType(Object, TypeCode)
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan.
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
Objek yang mengimplementasikan antarmuka IConvertible.
- typeCode
- TypeCode
Jenis objek yang akan dikembalikan.
Mengembalikan
Objek yang jenis yang mendasarnya typeCode
dan nilainya setara dengan value
.
-atau-
Referensi null (Nothing
di Visual Basic), jika value
null
dan typeCode
Empty, String, atau Object.
Pengecualian
Konversi ini tidak didukung.
-atau-
value
null
dan typeCode
menentukan jenis nilai.
-atau-
value
tidak mengimplementasikan antarmuka IConvertible.
value
tidak dalam format yang dikenali oleh jenis typeCode
.
value
mewakili angka yang berada di luar rentang jenis typeCode
.
typeCode
tidak valid.
Contoh
Contoh berikut mengilustrasikan cara menggunakan metode ChangeType(Object, TypeCode) untuk mengubah Object ke jenis yang ditentukan oleh parameter TypeCode, jika memungkinkan.
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
open System
let d = -2.345
let i = Convert.ChangeType(d, TypeCode.Int32) :?> int
printfn $"The Double {d} when converted to an Int32 is {i}"
let s = "12/12/2009"
let dt = Convert.ChangeType(s, typeof<DateTime>) :?> DateTime
printfn $"The String {s} when converted to a Date is {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
Keterangan
ChangeType(Object, TypeCode) adalah metode konversi tujuan umum yang mengonversi objek yang ditentukan oleh value
ke jenis yang telah ditentukan sebelumnya yang ditentukan oleh typeCode
. Parameter value
dapat menjadi objek dari jenis apa pun. Agar konversi berhasil, value
harus menerapkan antarmuka IConvertible, karena metode ini hanya membungkus panggilan ke metode IConvertible yang sesuai. Metode ini juga mengharuskan konversi value
ke typeCode
didukung.
Metode ChangeType(Object, TypeCode) tidak mendukung konversi value
ke jenis kustom. Untuk melakukan konversi seperti itu, panggil metode ChangeType(Object, Type).
Berlaku untuk
ChangeType(Object, Type, IFormatProvider)
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan. Parameter memasok informasi pemformatan khusus budaya.
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
Objek yang mengimplementasikan antarmuka IConvertible.
- conversionType
- Type
Jenis objek yang akan dikembalikan.
- provider
- IFormatProvider
Objek yang memasok informasi pemformatan khusus budaya.
Mengembalikan
Objek yang jenisnya conversionType
dan nilainya setara dengan value
.
-atau-
value
, jika Typevalue
dan conversionType
sama.
-atau-
Referensi null (Nothing
di Visual Basic), jika value
null
dan conversionType
bukan jenis nilai.
Pengecualian
Konversi ini tidak didukung.
-atau-
value
null
dan conversionType
adalah jenis nilai.
-atau-
value
tidak mengimplementasikan antarmuka IConvertible.
value
tidak dalam format untuk conversionType
dikenali oleh provider
.
value
mewakili angka yang berada di luar rentang conversionType
.
conversionType
null
.
Contoh
Contoh berikut mendefinisikan kelas Temperature
yang mengimplementasikan antarmuka IConvertible.
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);
}
}
open System
open System.Globalization
type Temperature(temperature: decimal) =
member _.Celsius = temperature
member _.Kelvin =
temperature + 273.15m
member _.Fahrenheit =
Math.Round(decimal (temperature * 9m / 5m + 32m), 2)
override _.ToString() =
temperature.ToString "N2" + "°C"
// IConvertible implementations.
interface IConvertible with
member _.GetTypeCode() =
TypeCode.Object
member _.ToBoolean(provider: IFormatProvider) =
temperature <> 0M
member _.ToByte(provider: IFormatProvider) =
if temperature < decimal Byte.MinValue || temperature > decimal Byte.MaxValue then
raise (OverflowException $"{temperature} is out of range of the Byte type.")
else
Decimal.ToByte temperature
member _.ToChar(provider: IFormatProvider) =
raise (InvalidCastException "Temperature to Char conversion is not supported.")
member _.ToDateTime(provider: IFormatProvider) =
raise (InvalidCastException "Temperature to DateTime conversion is not supported.")
member _.ToDecimal(provider: IFormatProvider) =
temperature
member _.ToDouble(provider: IFormatProvider) =
Decimal.ToDouble temperature
member _.ToInt16(provider: IFormatProvider) =
if temperature < decimal Int16.MinValue || temperature > decimal Int16.MaxValue then
raise (OverflowException $"{temperature} is out of range of the Int16 type.")
else
Decimal.ToInt16 temperature
member _.ToInt32(provider: IFormatProvider) =
if temperature < decimal Int32.MinValue || temperature > decimal Int32.MaxValue then
raise (OverflowException $"{temperature} is out of range of the Int32 type.")
else
Decimal.ToInt32 temperature
member _.ToInt64(provider: IFormatProvider) =
if temperature < decimal Int64.MinValue || temperature > decimal Int64.MaxValue then
raise (OverflowException $"{temperature} is out of range of the Int64 type.")
else
Decimal.ToInt64 temperature
member _.ToSByte(provider: IFormatProvider) =
if temperature < decimal SByte.MinValue || temperature > decimal SByte.MaxValue then
raise (OverflowException $"{temperature} is out of range of the SByte type.")
else
Decimal.ToSByte temperature
member _.ToSingle(provider: IFormatProvider) =
Decimal.ToSingle temperature
member _.ToString(provider: IFormatProvider) =
temperature.ToString("N2", provider) + "°C"
member this.ToType(conversionType: Type, provider: IFormatProvider) =
let this = this :> IConvertible
match Type.GetTypeCode conversionType with
| TypeCode.Boolean->
this.ToBoolean null
| TypeCode.Byte ->
this.ToByte null
| TypeCode.Char ->
this.ToChar null
| TypeCode.DateTime ->
this.ToDateTime null
| TypeCode.Decimal ->
this.ToDecimal null
| TypeCode.Double ->
this.ToDouble null
| TypeCode.Int16 ->
this.ToInt16 null
| TypeCode.Int32 ->
this.ToInt32 null
| TypeCode.Int64 ->
this.ToInt64 null
| TypeCode.Object ->
if typeof<Temperature>.Equals conversionType then
this
else
raise (InvalidCastException $"Conversion to a {conversionType.Name} is not supported.")
| TypeCode.SByte ->
this.ToSByte null
| TypeCode.Single ->
this.ToSingle null
| TypeCode.String ->
this.ToString provider
| TypeCode.UInt16 ->
this.ToUInt16 null
| TypeCode.UInt32->
this.ToUInt32 null
| TypeCode.UInt64->
this.ToUInt64 null
| _ ->
raise (InvalidCastException $"Conversion to {conversionType.Name} is not supported.")
member _.ToUInt16(provider: IFormatProvider) =
if temperature < decimal UInt16.MinValue || temperature > decimal UInt16.MaxValue then
raise (OverflowException $"{temperature} is out of range of the UInt16 type.")
else
Decimal.ToUInt16 temperature
member _.ToUInt32(provider: IFormatProvider) =
if temperature < decimal UInt32.MinValue || temperature > decimal UInt32.MaxValue then
raise (OverflowException $"{temperature} is out of range of the UInt32 type.")
else
Decimal.ToUInt32 temperature
member _.ToUInt64(provider: IFormatProvider) =
if temperature < decimal UInt64.MinValue || temperature > decimal UInt64.MaxValue then
raise (OverflowException $"{temperature} is out of range of the UInt64 type.")
else
Decimal.ToUInt64 temperature
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
Contoh berikut membuat instans kelas Temperature
dan memanggil metode ChangeType(Object, Type, IFormatProvider) untuk mengonversinya ke jenis numerik dasar yang didukung oleh .NET dan ke String. Ini menggambarkan bahwa metode ChangeType membungkus panggilan ke implementasi IConvertible jenis sumber.
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.
let cool = Temperature 5
let 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>; ]
let provider = CultureInfo "fr-FR"
for targetType in targetTypes do
try
let value = Convert.ChangeType(cool, targetType, provider)
printfn $"Converted {cool.GetType().Name} {cool} to {targetType.Name} {value}."
with
| :? InvalidCastException ->
printfn $"Unsupported {cool.GetType().Name} --> {targetType.Name} conversion."
| :? OverflowException ->
printfn $"{cool} is out of range of the {targetType.Name} type."
// 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.
Keterangan
ChangeType adalah metode konversi tujuan umum yang mengonversi objek yang ditentukan oleh value
menjadi conversionType
. Parameter value
dapat menjadi objek dari jenis apa pun, dan conversionType
juga dapat menjadi objek Type yang mewakili jenis dasar atau kustom apa pun. Agar konversi berhasil, value
harus menerapkan antarmuka IConvertible, karena metode ini hanya membungkus panggilan ke metode IConvertible yang sesuai. Metode ini mengharuskan konversi value
ke conversionType
didukung.
Parameter provider
adalah implementasi IFormatProvider yang menyediakan informasi pemformatan untuk konversi. Apakah dan bagaimana parameter ini digunakan tergantung pada implementasi IConvertible yang mendasar. Jika value
adalah jenis data dasar, provider
hanya digunakan untuk konversi berikut:
Konversi dari angka ke string, atau dari string ke angka.
provider
harus berupa objek CultureInfo, objek NumberFormatInfo, atau implementasi IFormatProvider kustom yang mengembalikan objek NumberFormatInfo. Namun, karena metode ChangeType(Object, TypeCode, IFormatProvider) melakukan konversi menggunakan penentu format "G" default, parameterprovider
tidak berpengaruh jikavalue
atau jenis target adalah bilangan bulat yang tidak ditandatangani. Jikaprovider
null
, objek CultureInfo yang mewakili budaya saat ini digunakan.Konversi dari nilai DateTime ke string, atau dari string ke nilai DateTime.
provider
harus berupa objek CultureInfo atau DateTimeFormatInfo. Jikaprovider
null
, objek CultureInfo yang mewakili budaya saat ini digunakan.
Jika value
adalah jenis yang ditentukan aplikasi, implementasi IConvertible-nya dapat menggunakan parameter provider
.
Catatan Bagi Pemanggil
Metode ChangeType(Object, Type, IFormatProvider) dapat mengonversi nilai enumerasi ke jenis lain. Namun, itu tidak dapat mengonversi jenis lain ke nilai enumerasi, bahkan jika jenis sumber adalah jenis enumerasi yang mendasar. Untuk mengonversi jenis menjadi nilai enumerasi, gunakan operator transmisi (di C#) atau fungsi konversi (di Visual Basic). Contoh berikut mengilustrasikan konversi ke dan dari nilai enumerasi Continent
.
using System;
public enum Continent
{
Africa, Antarctica, Asia, Australia, Europe,
NorthAmerica, SouthAmerica
};
public class Example
{
public static void Main()
{
// Convert a Continent to a Double.
Continent cont = Continent.NorthAmerica;
Console.WriteLine("{0:N2}",
Convert.ChangeType(cont, typeof(Double)));
// Convert a Double to a Continent.
Double number = 6.0;
try {
Console.WriteLine("{0}",
Convert.ChangeType(number, typeof(Continent)));
}
catch (InvalidCastException) {
Console.WriteLine("Cannot convert a Double to a Continent");
}
Console.WriteLine("{0}", (Continent) number);
}
}
// The example displays the following output:
// 5.00
// Cannot convert a Double to a Continent
// SouthAmerica
open System
type Continent =
| Africa = 0
| Antarctica = 1
| Asia = 2
| Australia = 3
| Europe = 4
| NorthAmerica = 5
| SouthAmerica = 6
// Convert a Continent to a Double.
let cont = Continent.NorthAmerica
printfn $"{Convert.ChangeType(cont, typeof<Double>):N2}"
// Convert a Double to a Continent.
let number = 6.0
try
printfn $"{Convert.ChangeType(number, typeof<Continent>)}"
with :? InvalidCastException ->
printfn "Cannot convert a Double to a Continent"
printfn $"{int number |> enum<Continent>}"
// The example displays the following output:
// 5.00
// Cannot convert a Double to a Continent
// SouthAmerica
Public Enum Continent As Integer
Africa = 0
Antarctica = 1
Asia = 2
Australia = 3
Europe = 4
NorthAmerica = 5
SouthAmerica = 6
End Enum
Module Example
Public Sub Main()
' Convert a Continent to a Double.
Dim cont As Continent = Continent.NorthAmerica
Console.WriteLine("{0:N2}",
Convert.ChangeType(cont, GetType(Double)))
' Convert a Double to a Continent.
Dim number As Double = 6.0
Try
Console.WriteLine("{0}",
Convert.ChangeType(number, GetType(Continent)))
Catch e As InvalidCastException
Console.WriteLine("Cannot convert a Double to a Continent")
End Try
Console.WriteLine("{0}", CType(number, Continent))
End Sub
End Module
' The example displays the following output:
' 5.00
' Cannot convert a Double to a Continent
' SouthAmerica
Metode ChangeType(Object, Type, IFormatProvider) dapat mengonversi jenis nullable ke jenis lain. Namun, itu tidak dapat mengonversi jenis lain ke nilai jenis nullable, bahkan jika conversionType
adalah jenis yang mendasar dari Nullable<T>. Untuk melakukan konversi, Anda dapat menggunakan operator transmisi (di C#) atau fungsi konversi (di Visual Basic). Contoh berikut mengilustrasikan konversi ke dan dari jenis yang dapat diubah ke null.
using System;
public class Example
{
public static void Main()
{
int? intValue1 = 12893;
double dValue1 = (double) Convert.ChangeType(intValue1, typeof(Double), null);
Console.WriteLine("{0} ({1})--> {2} ({3})", intValue1, intValue1.GetType().Name,
dValue1, dValue1.GetType().Name);
float fValue1 = 16.3478f;
int? intValue2 = (int) fValue1;
Console.WriteLine("{0} ({1})--> {2} ({3})", fValue1, fValue1.GetType().Name,
intValue2, intValue2.GetType().Name);
}
}
// The example displays the following output:
// 12893 (Int32)--> 12893 (Double)
// 16.3478 (Single)--> 16 (Int32)
open System
let intValue1 = Nullable 12893
let dValue1 = Convert.ChangeType(intValue1, typeof<Double>, null) :?> double
printfn $"{intValue1} ({intValue1.GetType().Name})--> {dValue1} ({dValue1.GetType().Name})"
let fValue1 = 16.3478f
let intValue2 = Nullable(int fValue1)
printfn $"{fValue1} ({fValue1.GetType().Name})--> {intValue2} ({intValue2.GetType().Name})"
// The example displays the following output:
// 12893 (Int32)--> 12893 (Double)
// 16.3478 (Single)--> 16 (Int32)
Module Example
Public Sub Main()
Dim intValue1 As Integer? = 12893
Dim dValue1 As Double = CType(Convert.ChangeType(intValue1, GetType(Double), Nothing), Double)
Console.WriteLine("{0} ({1})--> {2} ({3})", intValue1, intValue1.GetType().Name,
dValue1, dValue1.GetType().Name)
Dim fValue1 As Single = 16.3478
Dim intValue2 As Integer? = CType(fValue1, Integer)
Console.WriteLine("{0} ({1})--> {2} ({3})", fValue1, fValue1.GetType().Name,
intValue2, intValue2.GetType().Name)
End Sub
End Module
' The example displays the following output:
' 12893 (Int32)--> 12893 (Double)
' 16.3478 (Single)--> 16 (Int32)
Berlaku untuk
ChangeType(Object, TypeCode, IFormatProvider)
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
- Sumber:
- Convert.cs
Mengembalikan objek dari jenis yang ditentukan yang nilainya setara dengan objek yang ditentukan. Parameter memasok informasi pemformatan khusus budaya.
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
Objek yang mengimplementasikan antarmuka IConvertible.
- typeCode
- TypeCode
Jenis objek yang akan dikembalikan.
- provider
- IFormatProvider
Objek yang memasok informasi pemformatan khusus budaya.
Mengembalikan
Objek yang jenis yang mendasarnya typeCode
dan nilainya setara dengan value
.
-atau-
Referensi null (Nothing
di Visual Basic), jika value
null
dan typeCode
Empty, String, atau Object.
Pengecualian
Konversi ini tidak didukung.
-atau-
value
null
dan typeCode
menentukan jenis nilai.
-atau-
value
tidak mengimplementasikan antarmuka IConvertible.
value
tidak dalam format untuk jenis typeCode
yang dikenali oleh provider
.
value
mewakili angka yang berada di luar rentang jenis typeCode
.
typeCode
tidak valid.
Contoh
Contoh berikut mendefinisikan penyedia format kustom bernama InterceptProvider
yang menunjukkan kapan metode GetFormat dipanggil dan mengembalikan NumberFormatInfo untuk budaya fr-FR dan objek DateTimeFormatInfo untuk budaya en-US. Penyedia format ini digunakan dalam semua panggilan ke metode ChangeType(Object, TypeCode, IFormatProvider). Contoh kemudian membuat array dengan nilai Double dan DateTime dan melakukan panggilan berulang ke ChangeType(Object, TypeCode, IFormatProvider) dengan setiap nilai dan setiap anggota enumerasi TypeCode. Contoh mengilustrasikan ketika metode menggunakan parameter IFormatProvider dan juga mengilustrasikan penggunaan parameter provider
untuk melakukan pemformatan sensitif budaya.
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).
open System
open System.Globalization
type InterceptProvider() =
interface IFormatProvider with
member _.GetFormat(formatType: Type) =
if formatType = typeof<NumberFormatInfo> then
printfn " Returning a fr-FR numeric format provider."
CultureInfo("fr-FR").NumberFormat
elif formatType = typeof<DateTimeFormatInfo> then
printfn " Returning an en-US date/time format provider."
CultureInfo("en-US").DateTimeFormat
else
printfn $" Requesting a format provider of {formatType.Name}."
null
let values: obj[] = [| 103.5; DateTime(2010, 12, 26, 14, 34, 0)|]
let provider = InterceptProvider()
// Convert value to each of the types represented in TypeCode enum.
for value in values do
// Iterate types in TypeCode enum.
for enumType in Enum.GetValues typeof<TypeCode> :?> TypeCode[] do
match enumType with
| TypeCode.DBNull | TypeCode.Empty -> ()
| _ ->
try
printfn $"{value} ({value.GetType().Name}) --> {Convert.ChangeType(value, enumType, provider)} ({enumType})."
with
| :? InvalidCastException ->
printfn $"Cannot convert a {value.GetType().Name} to a {enumType}"
| :? OverflowException ->
printfn $"Overflow: {value} is out of the range of a {enumType}"
printfn ""
// 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).
Keterangan
ChangeType(Object, TypeCode, IFormatProvider) adalah metode konversi tujuan umum yang mengonversi objek yang ditentukan oleh value
ke jenis yang telah ditentukan sebelumnya yang ditentukan oleh typeCode
. Parameter value
dapat menjadi objek dari jenis apa pun. Agar konversi berhasil, value
harus menerapkan antarmuka IConvertible, karena metode ini hanya membungkus panggilan ke metode IConvertible yang sesuai. Metode ini juga mengharuskan konversi value
ke typeCode
didukung.
Metode ChangeType(Object, TypeCode, IFormatProvider) tidak mendukung konversi value
ke jenis kustom. Untuk melakukan konversi seperti itu, panggil metode ChangeType(Object, Type, IFormatProvider).
Parameter provider
adalah implementasi IFormatProvider yang menyediakan informasi pemformatan untuk konversi. Apakah dan bagaimana parameter ini digunakan tergantung pada implementasi IConvertible yang mendasar. Jika value
adalah jenis data dasar, provider
hanya digunakan untuk konversi berikut. Jika argumen null
IFormatProvider diteruskan ke metode ini, objek CultureInfo yang mewakili budaya saat ini digunakan.
Konversi dari angka ke string, atau dari string ke angka.
provider
harus berupa objek CultureInfo, objek NumberFormatInfo, atau implementasi IFormatProvider kustom yang mengembalikan objek NumberFormatInfo. Namun, karena metode ChangeType(Object, TypeCode, IFormatProvider) melakukan konversi menggunakan penentu format "G" default, parameterprovider
tidak berpengaruh jikavalue
atau jenis target adalah bilangan bulat yang tidak ditandatangani.Konversi dari nilai DateTime ke string, atau dari string ke nilai DateTime.
provider
harus berupa objek CultureInfo atau DateTimeFormatInfo.
Jika value
adalah jenis yang ditentukan aplikasi, implementasi IConvertible-nya dapat menggunakan parameter provider
.