Convert.ToByte Method (Object, IFormatProvider)
Converts the value of the specified object to an 8-bit unsigned integer, using the specified culture-specific formatting information.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- value
-
Type:
System.Object
An object that implements the IConvertible interface.
- provider
-
Type:
System.IFormatProvider
An object that supplies culture-specific formatting information.
Return Value
Type: System.ByteAn 8-bit unsigned integer that is equivalent to value, or zero if value is null.
| Exception | Condition |
|---|---|
| FormatException | value is not in the property format for a Byte value. |
| InvalidCastException | |
| OverflowException | value represents a number that is less than Byte.MinValue or greater than Byte.MaxValue. |
provider enables the user to specify culture-specific conversion information about the contents of value. The base types ignore provider; however, the parameter may be used if value is a user-defined type that implements the IConvertible interface.
The following example defines a ByteString class that implements the IConvertible interface. The class stores the string representation of a byte value along with a sign field, so that it is able to represent both signed and unsigned byte values.
Imports System.Globalization Public Enum SignBit As Integer Positive = 1 Zero = 0 Negative = -1 End Enum Public Structure ByteString : Implements IConvertible Private signBit As SignBit Private byteString As String Public Property Sign As SignBit Set signBit = value End Set Get Return signBit End Get End Property Public Property Value As String Set If value.Trim().Length > 2 Then Throw New ArgumentException("The string representation of a byte cannot have more than two characters.") Else byteString = value End If End Set Get Return byteString End Get End Property ' 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 signBit = SignBit.Zero Then Return False Else Return True End If End Function Public Function ToByte(provider As IFormatProvider) As Byte _ Implements IConvertible.ToByte If signBit = signBit.Negative Then Throw New OverflowException(String.Format("{0} is out of range of the Byte type.", Convert.ToSByte(byteString, 16))) Else Return Byte.Parse(byteString, NumberStyles.HexNumber) End If End Function Public Function ToChar(provider As IFormatProvider) As Char _ Implements IConvertible.ToChar If signBit = signBit.Negative Then Throw New OverflowException(String.Format("{0} is out of range of the Char type.", Convert.ToSByte(byteString, 16))) Else Dim byteValue As Byte = Byte.Parse(Me.byteString, NumberStyles.HexNumber) Return Convert.ToChar(byteValue) End If End Function Public Function ToDateTime(provider As IFormatProvider) As Date _ Implements IConvertible.ToDateTime Throw New InvalidCastException("ByteString to DateTime conversion is not supported.") End Function Public Function ToDecimal(provider As IFormatProvider) As Decimal _ Implements IConvertible.ToDecimal If signBit = signBit.Negative Then Dim byteValue As SByte = SByte.Parse(byteString, NumberStyles.HexNumber) Return Convert.ToDecimal(byteValue) Else Dim byteValue As Byte = Byte.Parse(byteString, NumberStyles.HexNumber) Return Convert.ToDecimal(byteValue) End If End Function Public Function ToDouble(provider As IFormatProvider) As Double _ Implements IConvertible.ToDouble If signBit = signBit.Negative Then Return Convert.ToDouble(SByte.Parse(byteString, NumberStyles.HexNumber)) Else Return Convert.ToDouble(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToInt16(provider As IFormatProvider) As Int16 _ Implements IConvertible.ToInt16 If signBit = signBit.Negative Then Return Convert.ToInt16(SByte.Parse(byteString, NumberStyles.HexNumber)) Else Return Convert.ToInt16(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToInt32(provider As IFormatProvider) As Int32 _ Implements IConvertible.ToInt32 If signBit = signBit.Negative Then Return Convert.ToInt32(SByte.Parse(byteString, NumberStyles.HexNumber)) Else Return Convert.ToInt32(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToInt64(provider As IFormatProvider) As Int64 _ Implements IConvertible.ToInt64 If signBit = signBit.Negative Then Return Convert.ToInt64(SByte.Parse(byteString, NumberStyles.HexNumber)) Else Return Convert.ToInt64(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToSByte(provider As IFormatProvider) As SByte _ Implements IConvertible.ToSByte If signBit = SignBit.Positive Then Try Return Convert.ToSByte(Byte.Parse(byteString, NumberStyles.HexNumber)) Catch e As OverflowException Throw New OverflowException(String.Format("{0} is outside the range of the SByte type.", _ Byte.Parse(byteString, NumberStyles.HexNumber)), e) End Try Else Return SByte.Parse(byteString, NumberStyles.HexNumber) End If End Function Public Function ToSingle(provider As IFormatProvider) As Single _ Implements IConvertible.ToSingle If signBit = signBit.Negative Then Return Convert.ToSingle(SByte.Parse(byteString, NumberStyles.HexNumber)) Else Return Convert.ToSingle(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Overloads Function ToString(provider As IFormatProvider) As String _ Implements IConvertible.ToString Return Me.byteString 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(ByteString).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(Nothing) 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 signBit = signBit.Negative Then Throw New OverflowException(String.Format("{0} is outside the range of the UInt16 type.", _ SByte.Parse(byteString, NumberStyles.HexNumber))) Else Return Convert.ToUInt16(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToUInt32(provider As IFormatProvider) As UInt32 _ Implements IConvertible.ToUInt32 If signBit = signBit.Negative Then Throw New OverflowException(String.Format("{0} is outside the range of the UInt32 type.", _ SByte.Parse(byteString, NumberStyles.HexNumber))) Else Return Convert.ToUInt32(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function Public Function ToUInt64(provider As IFormatProvider) As UInt64 _ Implements IConvertible.ToUInt64 If signBit = signBit.Negative Then Throw New OverflowException(String.Format("{0} is outside the range of the UInt64 type.", _ SByte.Parse(byteString, NumberStyles.HexNumber))) Else Return Convert.ToUInt64(Byte.Parse(byteString, NumberStyles.HexNumber)) End If End Function End Structure
The following example instantiates several ByteString objects and calls the ToByte(Object, IFormatProvider) method to convert them to byte values. It illustrates that the ToByte(Object, IFormatProvider) method wraps a call to the IConvertible.ToByte method of the object to be converted.
Module modMain Public Sub Main() Dim positiveByte As Byte = 216 Dim negativeByte As SByte = -101 Dim positiveString As New ByteString() positiveString.Sign = CType(Math.Sign(positiveByte), SignBit) positiveString.Value = positiveByte.ToString("X2") Dim negativeString As New ByteString() negativeString.Sign = CType(Math.Sign(negativeByte), SignBit) negativeString.Value = negativeByte.ToString("X2") Try Console.WriteLine("'{0}' converts to {1}.", positiveString.Value, Convert.ToByte(positiveString)) Catch e As OverflowException Console.WriteLine("0x{0} is outside the range of the Byte type.", positiveString.Value) End Try Try Console.WriteLine("'{0}' converts to {1}.", negativeString.Value, Convert.ToByte(negativeString)) Catch e As OverflowException Console.WriteLine("0x{0} is outside the range of the Byte type.", negativeString.Value) End Try End Sub End Module ' The example dosplays the following output: ' 'D8' converts to 216. ' 0x9B is outside the range of the Byte type.
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1