Convert.ToByte 方法

定義

將指定的值轉換為 8 位元不帶正負號的整數。Converts a specified value to an 8-bit unsigned integer.

多載

ToByte(String)

將指定之數字的字串表示,轉換為相等的 8 位元不帶正負號的整數。Converts the specified string representation of a number to an equivalent 8-bit unsigned integer.

ToByte(UInt16)

將指定的 16 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 16-bit unsigned integer to an equivalent 8-bit unsigned integer.

ToByte(UInt32)

將指定的 32 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 32-bit unsigned integer to an equivalent 8-bit unsigned integer.

ToByte(String, Int32)

將指定基底中數字的字串表示,轉換為相等的 8 位元不帶正負號的整數。Converts the string representation of a number in a specified base to an equivalent 8-bit unsigned integer.

ToByte(Object, IFormatProvider)

使用指定之特定文化特性格式資訊,將指定之物件的值轉換為 8 位元不帶正負號的整數。Converts the value of the specified object to an 8-bit unsigned integer, using the specified culture-specific formatting information.

ToByte(String, IFormatProvider)

使用指定之特定文化特性格式資訊,將指定之數字的字串表示轉換為相等的 8 位元不帶正負號的整數。Converts the specified string representation of a number to an equivalent 8-bit unsigned integer, using specified culture-specific formatting information.

ToByte(Single)

將指定之單精確度浮點數的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified single-precision floating-point number to an equivalent 8-bit unsigned integer.

ToByte(UInt64)

將指定的 64 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 64-bit unsigned integer to an equivalent 8-bit unsigned integer.

ToByte(SByte)

將指定的 8 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 8-bit signed integer to an equivalent 8-bit unsigned integer.

ToByte(Double)

將指定之雙精確度浮點數的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified double-precision floating-point number to an equivalent 8-bit unsigned integer.

ToByte(Int64)

將指定的 64 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 64-bit signed integer to an equivalent 8-bit unsigned integer.

ToByte(Byte)

傳回指定的 8 位元不帶正負號整數;不會執行實際的轉換。Returns the specified 8-bit unsigned integer; no actual conversion is performed.

ToByte(Char)

將指定的 Unicode 字元值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified Unicode character to the equivalent 8-bit unsigned integer.

ToByte(DateTime)

呼叫這個方法一律會擲回 InvalidCastExceptionCalling this method always throws InvalidCastException.

ToByte(Boolean)

將指定的布林值轉換為相等的 8 位元不帶正負號的整數。Converts the specified Boolean value to the equivalent 8-bit unsigned integer.

ToByte(Int16)

將指定的 16 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 16-bit signed integer to an equivalent 8-bit unsigned integer.

ToByte(Int32)

將指定的 32 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 32-bit signed integer to an equivalent 8-bit unsigned integer.

ToByte(Decimal)

將指定之十進位數字的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified decimal number to an equivalent 8-bit unsigned integer.

ToByte(Object)

將指定之物件的值轉換為 8 位元不帶正負號的整數。Converts the value of the specified object to an 8-bit unsigned integer.

ToByte(String)

將指定之數字的字串表示,轉換為相等的 8 位元不帶正負號的整數。Converts the specified string representation of a number to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::String ^ value);
public static byte ToByte (string value);
static member ToByte : string -> byte
Public Shared Function ToByte (value As String) As Byte

參數

value
String

字串,包含要轉換的數字。A string that contains the number to convert.

傳回

8 位元不帶正負號的整數,等於 value;而若 valuenull,則為零。An 8-bit unsigned integer that is equivalent to value, or zero if value is null.

例外狀況

value 不是由後面接著一連串數字 (0 到 9) 的任意符號所組成。value does not consist of an optional sign followed by a sequence of digits (0 through 9).

value 代表小於 MinValue 或大於 MaxValue 的數字。value represents a number that is less than MinValue or greater than MaxValue.

範例

下列範例會定義字串陣列,並嘗試將每個字串轉換成ByteThe following example defines a string array and attempts to convert each string to a Byte. 請注意,當null字串剖析為零時String.EmptyFormatException會擲回。Note that while a null string parses to zero, String.Empty throws a FormatException. 另請注意,雖然開頭和尾端空格剖析成功,但是格式化符號(例如貨幣符號、群組分隔符號或十進位分隔符號)則不會。Also note that while leading and trailing spaces parse successfully, formatting symbols, such as currency symbols, group separators, or decimal separators, do not.

using System;

public class Example
{
   public static void Main()
   {
      String[] values = { null, "", "0xC9", "C9", "101", "16.3", 
                          "$12", "$12.01", "-4", "1,032", "255",
                          "   16  " };
      foreach (var value in values) {
         try {
            byte number = Convert.ToByte(value);
            Console.WriteLine("'{0}' --> {1}", 
                              value == null ? "<null>" : value, number);
         }
         catch (FormatException) {
            Console.WriteLine("Bad Format: '{0}'", 
                              value == null ? "<null>" : value);
         }
         catch (OverflowException) {
            Console.WriteLine("OverflowException: '{0}'", value);
         }
      }
   }
}
// The example displays the following output:
//     '<null>' --> 0
//     Bad Format: ''
//     Bad Format: '0xC9'
//     Bad Format: 'C9'
//     '101' --> 101
//     Bad Format: '16.3'
//     Bad Format: '$12'
//     Bad Format: '$12.01'
//     OverflowException: '-4'
//     Bad Format: '1,032'
//     '255' --> 255
//     '   16  ' --> 16
Module Example
   Public Sub Main()
      Dim values() As String = { Nothing, "", "0xC9", "C9", "101", 
                                 "16.3", "$12", "$12.01", "-4", 
                                 "1,032", "255", "   16  " }
      For Each value In values
         Try 
            Dim number As Byte = Convert.ToByte(value)
            Console.WriteLine("'{0}' --> {1}", 
                              If(value Is Nothing, "<null>", value), number)
         Catch e As FormatException
            Console.WriteLine("Bad Format: '{0}'", 
                              If(value Is Nothing, "<null>", value))
         Catch e As OverflowException
            Console.WriteLine("OverflowException: '{0}'", value)
         End Try
      Next
   End Sub
End Module
' The example displays the following output:
'     '<null>' --> 0
'     Bad Format: ''
'     Bad Format: '0xC9'
'     Bad Format: 'C9'
'     '101' --> 101
'     Bad Format: '16.3'
'     Bad Format: '$12'
'     Bad Format: '$12.01'
'     OverflowException: '-4'
'     Bad Format: '1,032'
'     '255' --> 255
'     '   16  ' --> 16

備註

使用方法相當於傳遞valueByte.Parse(String)方法。 ToByte(String)Using the ToByte(String) method is equivalent to passing value to the Byte.Parse(String) method. value 是使用目前執行緒文化特性的格式化慣例來解譯。value is interpreted by using the formatting conventions of the current thread culture.

如果您不想在轉換失敗時處理例外狀況,您可以改為呼叫Byte.TryParse方法。If you prefer not to handle an exception if the conversion fails, you can call the Byte.TryParse method instead. 它會傳回值,指出轉換是否成功或失敗。 BooleanIt returns a Boolean value that indicates whether the conversion succeeded or failed.

另請參閱

ToByte(UInt16)

重要

此 API 不符合 CLS 規範。

將指定的 16 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 16-bit unsigned integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::UInt16 value);
[System.CLSCompliant(false)]
public static byte ToByte (ushort value);
static member ToByte : uint16 -> byte
Public Shared Function ToByte (value As UShort) As Byte

參數

value
UInt16

要轉換之 16 位元不帶正負號的整數。The 16-bit unsigned integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

屬性

例外狀況

value 大於 MaxValuevalue is greater than MaxValue.

範例

下列範例會將不帶正負號的16位整數陣列Byte轉換成值。The following example converts an array of unsigned 16-bit integers to Byte values.

ushort[] numbers = { UInt16.MinValue, 121, 340, UInt16.MaxValue };
byte result;
foreach (ushort number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       Converted the UInt16 value 0 to the Byte value 0.
//       Converted the UInt16 value 121 to the Byte value 121.
//       The UInt16 value 340 is outside the range of the Byte type.
//       The UInt16 value 65535 is outside the range of the Byte type.
Dim numbers() As UShort = { UInt16.MinValue, 121, 340, UInt16.MaxValue }
Dim result As Byte
For Each number As UShort In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       Converted the UInt16 value 0 to the Byte value 0.
'       Converted the UInt16 value 121 to the Byte value 121.
'       The UInt16 value 340 is outside the range of the Byte type.
'       The UInt16 value 65535 is outside the range of the Byte type.

ToByte(UInt32)

重要

此 API 不符合 CLS 規範。

將指定的 32 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 32-bit unsigned integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::UInt32 value);
[System.CLSCompliant(false)]
public static byte ToByte (uint value);
static member ToByte : uint32 -> byte
Public Shared Function ToByte (value As UInteger) As Byte

參數

value
UInt32

要轉換之 32 位元不帶正負號的整數。The 32-bit unsigned integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

屬性

例外狀況

value 大於 MaxValuevalue is greater than MaxValue.

範例

下列範例會將不帶正負號整數的Byte陣列轉換為值。The following example converts an array of unsigned integers to Byte values.

uint[] numbers = { UInt32.MinValue, 121, 340, UInt32.MaxValue };
byte result;
foreach (uint number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       Converted the UInt32 value 0 to the Byte value 0.
//       Converted the UInt32 value 121 to the Byte value 121.
//       The UInt32 value 340 is outside the range of the Byte type.
//       The UInt32 value 4294967295 is outside the range of the Byte type.
Dim numbers() As UInteger = { UInt32.MinValue, 121, 340, UInt32.MaxValue }
Dim result As Byte
For Each number As UInteger In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       Converted the UInt32 value 0 to the Byte value 0.
'       Converted the UInt32 value 121 to the Byte value 121.
'       The UInt32 value 340 is outside the range of the Byte type.
'       The UInt32 value 4294967295 is outside the range of the Byte type.

ToByte(String, Int32)

將指定基底中數字的字串表示,轉換為相等的 8 位元不帶正負號的整數。Converts the string representation of a number in a specified base to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::String ^ value, int fromBase);
public static byte ToByte (string value, int fromBase);
static member ToByte : string * int -> byte
Public Shared Function ToByte (value As String, fromBase As Integer) As Byte

參數

value
String

字串,包含要轉換的數字。A string that contains the number to convert.

fromBase
Int32

value 中數字的基底,必須是 2、8、10 或 16。The base of the number in value, which must be 2, 8, 10, or 16.

傳回

value 中之數字相等的 8 位元不帶正負號的整數;如果 valuenull,則為 0 (零)。An 8-bit unsigned integer that is equivalent to the number in value, or 0 (zero) if value is null.

例外狀況

fromBase 不是 2、8、10 或 16。fromBase is not 2, 8, 10, or 16.

-或--or- 代表非 10 進位不帶正負號數字的 value,有前置負號。value, which represents a non-base 10 unsigned number, is prefixed with a negative sign.

valueEmptyvalue is Empty.

value 所包含的字元在 fromBase 指定的基底中不是有效數字。value contains a character that is not a valid digit in the base specified by fromBase. 如果 value 中的第一個字元無效,例外狀況訊息會指出沒有數字可進行轉換;否則訊息會指出 value 包含無效的尾端字元。The exception message indicates that there are no digits to convert if the first character in value is invalid; otherwise, the message indicates that value contains invalid trailing characters.

代表 10 進位不帶正負號數字的 value,有前置負號。value, which represents a base 10 unsigned number, is prefixed with a negative sign.

-或--or- value 代表小於 MinValue 或大於 MaxValue 的數字。value represents a number that is less than MinValue or greater than MaxValue.

範例

下列範例會交替嘗試解讀字串陣列,做為二進位、八進位、十進位和十六進位值的標記法。The following example alternately attempts to interpret an array of strings as the representation of binary, octal, decimal, and hexadecimal values.

using System;

public class Example
{
   public static void Main()
   {
      int[] bases = { 2, 8, 10, 16 };
      string[] values = { "-1", "1", "08", "0F", "11" , "12", "30",                
                          "101", "255", "FF", "10000000", "80" };
      byte number;
      foreach (int numBase in bases)
      {
         Console.WriteLine("Base {0}:", numBase);
         foreach (string value in values)
         {
            try {
               number = Convert.ToByte(value, numBase);
               Console.WriteLine("   Converted '{0}' to {1}.", value, number);
            }   
            catch (FormatException) {
               Console.WriteLine("   '{0}' is not in the correct format for a base {1} byte value.", 
                                 value, numBase);
            }                     
            catch (OverflowException) {
               Console.WriteLine("   '{0}' is outside the range of the Byte type.", value);
            }   
            catch (ArgumentException) {
               Console.WriteLine("   '{0}' is invalid in base {1}.", value, numBase);
            }
         }                                 
      } 
   }
}
// The example displays the following output:
//    Base 2:
//       '-1' is invalid in base 2.
//       Converted '1' to 1.
//       '08' is not in the correct format for a base 2 conversion.
//       '0F' is not in the correct format for a base 2 conversion.
//       Converted '11' to 3.
//       '12' is not in the correct format for a base 2 conversion.
//       '30' is not in the correct format for a base 2 conversion.
//       Converted '101' to 5.
//       '255' is not in the correct format for a base 2 conversion.
//       'FF' is not in the correct format for a base 2 conversion.
//       Converted '10000000' to 128.
//       '80' is not in the correct format for a base 2 conversion.
//    Base 8:
//       '-1' is invalid in base 8.
//       Converted '1' to 1.
//       '08' is not in the correct format for a base 8 conversion.
//       '0F' is not in the correct format for a base 8 conversion.
//       Converted '11' to 9.
//       Converted '12' to 10.
//       Converted '30' to 24.
//       Converted '101' to 65.
//       Converted '255' to 173.
//       'FF' is not in the correct format for a base 8 conversion.
//       '10000000' is outside the range of the Byte type.
//       '80' is not in the correct format for a base 8 conversion.
//    Base 10:
//       '-1' is outside the range of the Byte type.
//       Converted '1' to 1.
//       Converted '08' to 8.
//       '0F' is not in the correct format for a base 10 conversion.
//       Converted '11' to 11.
//       Converted '12' to 12.
//       Converted '30' to 30.
//       Converted '101' to 101.
//       Converted '255' to 255.
//       'FF' is not in the correct format for a base 10 conversion.
//       '10000000' is outside the range of the Byte type.
//       Converted '80' to 80.
//    Base 16:
//       '-1' is invalid in base 16.
//       Converted '1' to 1.
//       Converted '08' to 8.
//       Converted '0F' to 15.
//       Converted '11' to 17.
//       Converted '12' to 18.
//       Converted '30' to 48.
//       '101' is outside the range of the Byte type.
//       '255' is outside the range of the Byte type.
//       Converted 'FF' to 255.
//       '10000000' is outside the range of the Byte type.
//       Converted '80' to 128.
Module Example
   Public Sub Main()
      Dim bases() As Integer = { 2, 8, 10, 16 }
      Dim values() As String = { "-1", "1", "08", "0F", "11" , "12", "30", _                
                                  "101", "255", "FF", "10000000", "80" }
      Dim number As Byte
      For Each base As Integer In bases
         Console.WriteLine("Base {0}:", base)
         For Each value As String In values
            Try
               number = Convert.ToByte(value, base)
               Console.WriteLine("   Converted '{0}' to {1}.", value, number)
            Catch e As FormatException
               Console.WriteLine("   '{0}' is not in the correct format for a base {1} conversion.", _
                                 value, base)
            Catch e As OverflowException
               Console.WriteLine("   '{0}' is outside the range of the Byte type.", value)
            Catch e As ArgumentException
               Console.WriteLine("   '{0}' is invalid in base {1}.", value, base)
            End Try   
         Next                                 
      Next 
   End Sub
End Module
' The example displays the following output:
'    Base 2:
'       '-1' is invalid in base 2.
'       Converted '1' to 1.
'       '08' is not in the correct format for a base 2 conversion.
'       '0F' is not in the correct format for a base 2 conversion.
'       Converted '11' to 3.
'       '12' is not in the correct format for a base 2 conversion.
'       '30' is not in the correct format for a base 2 conversion.
'       Converted '101' to 5.
'       '255' is not in the correct format for a base 2 conversion.
'       'FF' is not in the correct format for a base 2 conversion.
'       Converted '10000000' to 128.
'       '80' is not in the correct format for a base 2 conversion.
'    Base 8:
'       '-1' is invalid in base 8.
'       Converted '1' to 1.
'       '08' is not in the correct format for a base 8 conversion.
'       '0F' is not in the correct format for a base 8 conversion.
'       Converted '11' to 9.
'       Converted '12' to 10.
'       Converted '30' to 24.
'       Converted '101' to 65.
'       Converted '255' to 173.
'       'FF' is not in the correct format for a base 8 conversion.
'       '10000000' is outside the range of the Byte type.
'       '80' is not in the correct format for a base 8 conversion.
'    Base 10:
'       '-1' is outside the range of the Byte type.
'       Converted '1' to 1.
'       Converted '08' to 8.
'       '0F' is not in the correct format for a base 10 conversion.
'       Converted '11' to 11.
'       Converted '12' to 12.
'       Converted '30' to 30.
'       Converted '101' to 101.
'       Converted '255' to 255.
'       'FF' is not in the correct format for a base 10 conversion.
'       '10000000' is outside the range of the Byte type.
'       Converted '80' to 80.
'    Base 16:
'       '-1' is invalid in base 16.
'       Converted '1' to 1.
'       Converted '08' to 8.
'       Converted '0F' to 15.
'       Converted '11' to 17.
'       Converted '12' to 18.
'       Converted '30' to 48.
'       '101' is outside the range of the Byte type.
'       '255' is outside the range of the Byte type.
'       Converted 'FF' to 255.
'       '10000000' is outside the range of the Byte type.
'       Converted '80' to 128.

備註

如果fromBase是16,您可以在value參數所指定的數位前面加上 "0x" 或 "0x"。If fromBase is 16, you can prefix the number specified by the value parameter with "0x" or "0X".

因為資料類型只支援不帶正負號的ToByte(String, Int32)值,所以value此方法會假設使用不帶正負號的二進位標記法來表示。 ByteBecause the Byte data type supports unsigned values only, the ToByte(String, Int32) method assumes that value is expressed using unsigned binary representation. 換句話說,所有八位都是用來代表數值,而且不存在正負號位。In other words, all eight bits are used to represent the numeric value, and a sign bit is absent. 因此,您可以撰寫程式碼,其中的帶正負號的位元組值超出Byte資料類型的範圍會轉換Byte成值,而不會有方法擲回例外狀況。As a result, it is possible to write code in which a signed byte value that is out of the range of the Byte data type is converted to a Byte value without the method throwing an exception. 下列範例會將MinValue轉換為其十六進位字串表示,然後ToByte(String, Int32)呼叫方法。The following example converts MinValue to its hexadecimal string representation, and then calls the ToByte(String, Int32) method. 方法不會擲回例外狀況,而是會顯示訊息「0x80 轉換成128」。Instead of throwing an exception, the method displays the message, "0x80 converts to 128."

// Create a hexadecimal value out of range of the Byte type.
string value = SByte.MinValue.ToString("X");
// Convert it back to a number.
try
{
   byte number = Convert.ToByte(value, 16);
   Console.WriteLine("0x{0} converts to {1}.", value, number);
}   
catch (OverflowException)
{
   Console.WriteLine("Unable to convert '0x{0}' to a byte.", value);
}   
' Create a hexadecimal value out of range of the Byte type.
Dim value As String = SByte.MinValue.ToString("X")
' Convert it back to a number.
Try
   Dim number As Byte = Convert.ToByte(value, 16)
   Console.WriteLine("0x{0} converts to {1}.", value, number)
Catch e As OverflowException
   Console.WriteLine("Unable to convert '0x{0}' to a byte.", value)
End Try   

執行二進位作業或數值轉換時,開發人員必須負責確認方法或運算子使用適當的數值標記法來解讀特定的值。When performing binary operations or numeric conversions, it is always the responsibility of the developer to verify that a method or operator is using the appropriate numeric representation to interpret a particular value. 下列範例說明一項技術,可確保方法在將十六進位字串標記法轉換成Byte值時,不會不當使用不帶正負號的二進位標記法。The following example illustrates one technique for ensuring that the method does not inappropriately use unsigned binary representation when it converts a hexadecimal string representation to a Byte value. 此範例會在將該值轉換成其字串表示時,判斷某個值是否代表帶正負號或不帶正負號的整數。The example determines whether a value represents a signed or an unsigned integer while it is converting that value to its string representation. 當範例將值轉換回Byte值時,它會檢查原始值是否為帶正負號的整數。When the example converts the value back to a Byte value, it checks whether the original value was a signed integer. 如果是,而且如果設定了高序位位(表示值是負數,而它使用兩個補數,而不是不帶正負號的二進位標記法),則方法會擲回例外狀況。If so, and if its high-order bit is set (which indicates that the value is negative and that it uses two's complement instead of unsigned binary representation), the method throws an exception.

// Create a negative hexadecimal value out of range of the Byte type.
sbyte sourceNumber = SByte.MinValue;
bool isSigned = Math.Sign((sbyte)sourceNumber.GetType().GetField("MinValue").GetValue(null)) == -1;
string value = sourceNumber.ToString("X");
byte targetNumber;
try
{
   targetNumber = Convert.ToByte(value, 16);
   if (isSigned && ((targetNumber & 0x80) != 0))
      throw new OverflowException();
   else 
      Console.WriteLine("0x{0} converts to {1}.", value, targetNumber);
}
catch (OverflowException)
{
   Console.WriteLine("Unable to convert '0x{0}' to an unsigned byte.", value);
} 
// Displays the following to the console:
//    Unable to convert '0x80' to an unsigned byte.     
' Create a negative hexadecimal value out of range of the Byte type.
Dim sourceNumber As SByte = SByte.MinValue
Dim isSigned As Boolean = Math.Sign(sourceNumber.MinValue) = -1
Dim value As String = sourceNumber.ToString("X")
Dim targetNumber As Byte
Try
   targetNumber = Convert.ToByte(value, 16)
   If isSigned And ((targetNumber And &H80) <> 0) Then
      Throw New OverflowException()
   Else 
      Console.WriteLine("0x{0} converts to {1}.", value, targetNumber)
   End If    
Catch e As OverflowException
   Console.WriteLine("Unable to convert '0x{0}' to an unsigned byte.", value)
End Try 
' Displays the following to the console:
'    Unable to convert '0x80' to an unsigned byte.     

ToByte(Object, IFormatProvider)

使用指定之特定文化特性格式資訊,將指定之物件的值轉換為 8 位元不帶正負號的整數。Converts the value of the specified object to an 8-bit unsigned integer, using the specified culture-specific formatting information.

public:
 static System::Byte ToByte(System::Object ^ value, IFormatProvider ^ provider);
public static byte ToByte (object value, IFormatProvider provider);
static member ToByte : obj * IFormatProvider -> byte
Public Shared Function ToByte (value As Object, provider As IFormatProvider) As Byte

參數

value
Object

實作 IConvertible 介面的物件。An object that implements the IConvertible interface.

provider
IFormatProvider

物件,提供特定文化特性格式資訊。An object that supplies culture-specific formatting information.

傳回

8 位元不帶正負號的整數,等於 value;而若 valuenull,則為零。An 8-bit unsigned integer that is equivalent to value, or zero if value is null.

例外狀況

value 的屬性格式不適用於 Byte 值。value is not in the property format for a Byte value.

value 未實作 IConvertiblevalue does not implement IConvertible.

-或--or- 不支援從 value 轉換至 Byte 類型。Conversion from value to the Byte type is not supported.

value 代表小於 MinValue 或大於 MaxValue 的數字。value represents a number that is less than MinValue or greater than MaxValue.

範例

下列範例定義一個實作 ByteString 介面的 IConvertible 類別。The following example defines a ByteString class that implements the IConvertible interface. 類別會儲存位元組值的字串表示以及正負號欄位,讓它能夠同時代表帶正負號和不帶正負號的位元組值。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.

using System;
using System.Globalization;

public enum SignBit { Negative=-1, Zero=0, Positive=1 };

public struct ByteString : IConvertible
{
   private SignBit signBit;
   private string byteString;
   
   public SignBit Sign
   { 
      set { signBit = value; }
      get { return signBit; }
   }

   public string Value
   { 
      set {
         if (value.Trim().Length > 2)
            throw new ArgumentException("The string representation of a byte cannot have more than two characters.");
         else
            byteString = value;
      }
      get { return byteString; }
   }
   
   // IConvertible implementations.
   public TypeCode GetTypeCode() {
      return TypeCode.Object;
   }
   
   public bool ToBoolean(IFormatProvider provider)
   {
      if (signBit == SignBit.Zero)
         return false;
      else
         return true;
   } 
   
   public byte ToByte(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         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);
   }
   
   public char ToChar(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative) { 
         throw new OverflowException(String.Format("{0} is out of range of the Char type.", Convert.ToSByte(byteString, 16)));
      }
      else {
         byte byteValue = Byte.Parse(this.byteString, NumberStyles.HexNumber);
         return Convert.ToChar(byteValue);
      }                
   } 
   
   public DateTime ToDateTime(IFormatProvider provider)
   {
      throw new InvalidCastException("ByteString to DateTime conversion is not supported.");
   }
   
   public decimal ToDecimal(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative) 
      {
         sbyte byteValue = SByte.Parse(byteString, NumberStyles.HexNumber);
         return Convert.ToDecimal(byteValue);
      }
      else 
      {
         byte byteValue = Byte.Parse(byteString, NumberStyles.HexNumber);
         return Convert.ToDecimal(byteValue);
      }
   }
   
   public double ToDouble(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         return Convert.ToDouble(SByte.Parse(byteString, NumberStyles.HexNumber));
      else
         return Convert.ToDouble(Byte.Parse(byteString, NumberStyles.HexNumber));
   }   
   
   public short ToInt16(IFormatProvider provider) 
   {
      if (signBit == SignBit.Negative)
         return Convert.ToInt16(SByte.Parse(byteString, NumberStyles.HexNumber));
      else
         return Convert.ToInt16(Byte.Parse(byteString, NumberStyles.HexNumber));
   }
   
   public int ToInt32(IFormatProvider provider) 
   {
      if (signBit == SignBit.Negative)
         return Convert.ToInt32(SByte.Parse(byteString, NumberStyles.HexNumber));
      else
         return Convert.ToInt32(Byte.Parse(byteString, NumberStyles.HexNumber));
   }
   
   public long ToInt64(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         return Convert.ToInt64(SByte.Parse(byteString, NumberStyles.HexNumber));
      else
         return Convert.ToInt64(Byte.Parse(byteString, NumberStyles.HexNumber));
   }
   
   public sbyte ToSByte(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         try {
            return Convert.ToSByte(Byte.Parse(byteString, NumberStyles.HexNumber));
         }
         catch (OverflowException e) {
            throw new OverflowException(String.Format("{0} is outside the range of the SByte type.", 
                                                   Byte.Parse(byteString, NumberStyles.HexNumber)), e);
         }
      else   
         return SByte.Parse(byteString, NumberStyles.HexNumber);
   }

   public float ToSingle(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         return Convert.ToSingle(SByte.Parse(byteString, NumberStyles.HexNumber));
      else
         return Convert.ToSingle(Byte.Parse(byteString, NumberStyles.HexNumber));
   }

   public string ToString(IFormatProvider provider)
   {
      return "0x" + this.byteString;
   }
   
   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(ByteString).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(null);
         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 UInt16 ToUInt16(IFormatProvider provider) 
   {
      if (signBit == SignBit.Negative)
         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));
   }

   public UInt32 ToUInt32(IFormatProvider provider)
   {
      if (signBit == SignBit.Negative)
         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));
   }
   
   public UInt64 ToUInt64(IFormatProvider provider) 
   {
      if (signBit == SignBit.Negative)
         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));
   }
}
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

下列範例會具現ByteString化數個物件ToByte(Object, IFormatProvider) ,並呼叫方法,將它們轉換成位元組值。The following example instantiates several ByteString objects and calls the ToByte(Object, IFormatProvider) method to convert them to byte values. 它說明ToByte(Object, IFormatProvider)方法會包裝呼叫IConvertible.ToByte要轉換之物件的方法。It illustrates that the ToByte(Object, IFormatProvider) method wraps a call to the IConvertible.ToByte method of the object to be converted.

public class Class1
{
   public static void Main()
   {
      byte positiveByte = 216;
      sbyte negativeByte = -101;
      
      
      ByteString positiveString = new ByteString();
      positiveString.Sign = (SignBit) Math.Sign(positiveByte);
      positiveString.Value = positiveByte.ToString("X2");
      
      ByteString negativeString = new ByteString();
      negativeString.Sign = (SignBit) Math.Sign(negativeByte);
      negativeString.Value = negativeByte.ToString("X2");
      
      try {
         Console.WriteLine("'{0}' converts to {1}.", positiveString.Value, Convert.ToByte(positiveString));
      }
      catch (OverflowException) {
         Console.WriteLine("0x{0} is outside the range of the Byte type.", positiveString.Value);
      }

      try {
         Console.WriteLine("'{0}' converts to {1}.", negativeString.Value, Convert.ToByte(negativeString));
      }
      catch (OverflowException) {
         Console.WriteLine("0x{0} is outside the range of the Byte type.", negativeString.Value);
      }   
   }
}
// The example displays the following output:
//       'D8' converts to 216.
//       0x9B is outside the range of the Byte type.
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.

備註

provider可讓使用者指定有關內容value的特定文化特性轉換資訊。provider enables the user to specify culture-specific conversion information about the contents of value. 基底類型會provider忽略; 不過,如果value是可實作為IConvertible介面的使用者定義型別,則可以使用參數。The base types ignore provider; however, the parameter may be used if value is a user-defined type that implements the IConvertible interface.

ToByte(String, IFormatProvider)

使用指定之特定文化特性格式資訊,將指定之數字的字串表示轉換為相等的 8 位元不帶正負號的整數。Converts the specified string representation of a number to an equivalent 8-bit unsigned integer, using specified culture-specific formatting information.

public:
 static System::Byte ToByte(System::String ^ value, IFormatProvider ^ provider);
public static byte ToByte (string value, IFormatProvider provider);
static member ToByte : string * IFormatProvider -> byte
Public Shared Function ToByte (value As String, provider As IFormatProvider) As Byte

參數

value
String

字串,包含要轉換的數字。A string that contains the number to convert.

provider
IFormatProvider

物件,提供特定文化特性格式資訊。An object that supplies culture-specific formatting information.

傳回

8 位元不帶正負號的整數,等於 value;而若 valuenull,則為零。An 8-bit unsigned integer that is equivalent to value, or zero if value is null.

例外狀況

value 不是由後面接著一連串數字 (0 到 9) 的任意符號所組成。value does not consist of an optional sign followed by a sequence of digits (0 through 9).

value 代表小於 MinValue 或大於 MaxValue 的數字。value represents a number that is less than MinValue or greater than MaxValue.

範例

下列範例會建立自訂NumberFormatInfo物件,將正號定義為 "pos",並將負號做為 "neg",以用於呼叫ToByte(String, IFormatProvider)方法。The following example creates a custom NumberFormatInfo object that defines the positive sign as "pos" and the negative sign as "neg", which it uses in calls to the ToByte(String, IFormatProvider) method. 然後,它會ToByte(String, IFormatProvider)重複呼叫方法,將字串陣列中的每個元素Byte轉換成一個值。It then calls the ToByte(String, IFormatProvider) method repeatedly to convert each element in a string array to a Byte value.

using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      // Create a NumberFormatInfo object and set several of its
      // properties that apply to unsigned bytes.
      NumberFormatInfo provider = new NumberFormatInfo();

      // These properties affect the conversion.
      provider.PositiveSign = "pos ";
      provider.NegativeSign = "neg ";

      // This property does not affect the conversion.
      // The input string cannot have a decimal separator.
      provider.NumberDecimalSeparator = ".";
      
      // Define an array of numeric strings.
      string[] numericStrings = { "234", "+234", "pos 234", "234.", "255", 
                                  "256", "-1" };

      foreach (string numericString in numericStrings)
      {
         Console.Write("'{0,-8}' ->   ", numericString);
         try {
            byte number = Convert.ToByte(numericString, provider);
            Console.WriteLine(number);
         }   
         catch (FormatException) {
            Console.WriteLine("Incorrect Format");
         }                             
         catch (OverflowException) {
            Console.WriteLine("Overflows a Byte");
         }   
      }
   }
}
// The example displays the following output:
//       '234     ' ->   234
//       '+234    ' ->   Incorrect Format
//       'pos 234 ' ->   234
//       '234.    ' ->   Incorrect Format
//       '255     ' ->   255
//       '256     ' ->   Overflows a Byte
//       '-1      ' ->   Incorrect Format
Imports System.Globalization

Module Example
   Public Sub Main()
      ' Create a NumberFormatInfo object and set several of its
      ' properties that apply to unsigned bytes.
      Dim provider As New NumberFormatInfo()
      With provider 
         ' These properties affect the conversion.
         .PositiveSign = "pos "
         .NegativeSign = "neg "

         ' This property does not affect the conversion.
         ' The input string cannot have a decimal separator.
         .NumberDecimalSeparator = "."
      End With
      
      ' Define an array of numeric strings.
      Dim numericStrings() As String = { "234", "+234", "pos 234", "234.", _
                                         "255", "256", "-1" }

      For Each numericString As String In numericStrings
         Console.Write("'{0,-8}' ->   ", numericString)
         Try
            Dim number As Byte = Convert.ToByte(numericString, provider)
            Console.WriteLine(number)
         Catch ex As FormatException
            Console.WriteLine("Incorrect Format")                          
         Catch ex As OverflowException
            Console.WriteLine("Overflows a Byte")
         End Try   
      Next
   End Sub   
End Module 
' The example displays the following output:
'       '234     ' ->   234
'       '+234    ' ->   Incorrect Format
'       'pos 234 ' ->   234
'       '234.    ' ->   Incorrect Format
'       '255     ' ->   255
'       '256     ' ->   Overflows a Byte
'       '-1      ' ->   Incorrect Format

備註

provider是取得NumberFormatInfo物件的實例。IFormatProviderprovider is an IFormatProvider instance that obtains a NumberFormatInfo object. 物件提供有關格式的value特定文化特性資訊。 NumberFormatInfoThe NumberFormatInfo object provides culture-specific information about the format of value. 如果providernull ,NumberFormatInfo則會使用目前文化特性的物件。If provider is null, the NumberFormatInfo object for the current culture is used.

如果您不想在轉換失敗時處理例外狀況,您可以改為呼叫Byte.TryParse方法。If you prefer not to handle an exception if the conversion fails, you can call the Byte.TryParse method instead. 它會傳回值,指出轉換是否成功或失敗。 BooleanIt returns a Boolean value that indicates whether the conversion succeeded or failed.

另請參閱

ToByte(Single)

將指定之單精確度浮點數的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified single-precision floating-point number to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(float value);
public static byte ToByte (float value);
static member ToByte : single -> byte
Public Shared Function ToByte (value As Single) As Byte

參數

value
Single

單精確度浮點數。A single-precision floating-point number.

傳回

value,四捨五入為最接近的 8 位元不帶正負號整數。value, rounded to the nearest 8-bit unsigned integer. 如果 value 介於兩個整數正中間時,則傳回偶數;也就是 4.5 會轉換為 4,5.5 會轉換為 6。If value is halfway between two whole numbers, the even number is returned; that is, 4.5 is converted to 4, and 5.5 is converted to 6.

例外狀況

value 大於 MaxValue 或小於 MinValuevalue is greater than MaxValue or less than MinValue.

範例

下列範例會將Single值轉換Byte為。The following example converts a Single value to a Byte.

public:
   void ConvertByteSingle( Byte byteVal )
   {
      float floatVal;
      
      // Byte to float conversion will not overflow.
      floatVal = System::Convert::ToSingle( byteVal );
      System::Console::WriteLine( "The Byte as a float is {0}.",
         floatVal );
      
      // Float to Byte conversion can overflow.
      try
      {
         byteVal = System::Convert::ToByte( floatVal );
         System::Console::WriteLine( "The float as a Byte is {0}.",
         byteVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine(
            "The float value is too large for a Byte." );
      }
   }
public void ConvertByteSingle(byte byteVal) {
    float floatVal;

    // Byte to float conversion will not overflow.
    floatVal = System.Convert.ToSingle(byteVal);
    System.Console.WriteLine("The byte as a float is {0}.",
        floatVal);

    // Float to byte conversion can overflow.
    try {
        byteVal = System.Convert.ToByte(floatVal);
        System.Console.WriteLine("The float as a byte is {0}.",
            byteVal);
    }
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "The float value is too large for a byte.");
    }
}
Public Sub ConvertByteSingle(ByVal byteVal As Byte)
    Dim singleVal As Single

    ' Byte to float conversion will not overflow.
    singleVal = System.Convert.ToSingle(byteVal)
    System.Console.WriteLine("The byte as a single is {0}.", _
                              singleVal)

    ' Single to byte conversion can overflow.
    Try
        byteVal = System.Convert.ToByte(singleVal)
        System.Console.WriteLine("The single as a byte is {0}.", _
                                  byteVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in single-to-byte conversion.")
    End Try
End Sub

另請參閱

ToByte(UInt64)

重要

此 API 不符合 CLS 規範。

將指定的 64 位元不帶正負號整數的值,轉換為相等的 8 位元不帶正負號整數。Converts the value of the specified 64-bit unsigned integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::UInt64 value);
[System.CLSCompliant(false)]
public static byte ToByte (ulong value);
static member ToByte : uint64 -> byte
Public Shared Function ToByte (value As ULong) As Byte

參數

value
UInt64

要轉換之 64 位元不帶正負號的整數。The 64-bit unsigned integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

屬性

例外狀況

value 大於 MaxValuevalue is greater than MaxValue.

範例

下列範例會將不帶正負號的長整數Byte陣列轉換成值。The following example converts an array of unsigned long integers to Byte values.

ulong[] numbers= { UInt64.MinValue, 121, 340, UInt64.MaxValue };
byte result;
foreach (ulong number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException)
   {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       Converted the UInt64 value 0 to the Byte value 0.
//       Converted the UInt64 value 121 to the Byte value 121.
//       The UInt64 value 340 is outside the range of the Byte type.
//       The UInt64 value 18446744073709551615 is outside the range of the Byte type.
Dim numbers() As ULong = { UInt64.MinValue, 121, 340, UInt64.MaxValue }
Dim result As Byte
For Each number As ULong In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       Converted the UInt64 value 0 to the Byte value 0.
'       Converted the UInt64 value 121 to the Byte value 121.
'       The UInt64 value 340 is outside the range of the Byte type.
'       The UInt64 value 18446744073709551615 is outside the range of the Byte type.

ToByte(SByte)

重要

此 API 不符合 CLS 規範。

將指定的 8 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 8-bit signed integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::SByte value);
[System.CLSCompliant(false)]
public static byte ToByte (sbyte value);
static member ToByte : sbyte -> byte
Public Shared Function ToByte (value As SByte) As Byte

參數

value
SByte

要轉換的 8 位元帶正負號的整數。The 8-bit signed integer to be converted.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

屬性

例外狀況

value 小於 MinValuevalue is less than MinValue.

範例

下列範例會將值的SByte陣列轉換成Byte值。The following example converts an array of SByte values to Byte values.

sbyte[] numbers = { SByte.MinValue, -1, 0, 10, SByte.MaxValue };
byte result;
foreach (sbyte number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException)
   {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       The SByte value -128 is outside the range of the Byte type.
//       The SByte value -1 is outside the range of the Byte type.
//       Converted the SByte value 0 to the Byte value 0.
//       Converted the SByte value 10 to the Byte value 10.
//       Converted the SByte value 127 to the Byte value 127.
Dim numbers() As SByte = { SByte.MinValue, -1, 0, 10, SByte.MaxValue }
Dim result As Byte
For Each number As SByte In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       The SByte value -128 is outside the range of the Byte type.
'       The SByte value -1 is outside the range of the Byte type.
'       Converted the SByte value 0 to the Byte value 0.
'       Converted the SByte value 10 to the Byte value 10.
'       Converted the SByte value 127 to the Byte value 127.

ToByte(Double)

將指定之雙精確度浮點數的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified double-precision floating-point number to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(double value);
public static byte ToByte (double value);
static member ToByte : double -> byte
Public Shared Function ToByte (value As Double) As Byte

參數

value
Double

要轉換的雙精確度浮點數。The double-precision floating-point number to convert.

傳回

value,四捨五入為最接近的 8 位元不帶正負號整數。value, rounded to the nearest 8-bit unsigned integer. 如果 value 介於兩個整數正中間時,則傳回偶數;也就是 4.5 會轉換為 4,5.5 會轉換為 6。If value is halfway between two whole numbers, the even number is returned; that is, 4.5 is converted to 4, and 5.5 is converted to 6.

例外狀況

value 大於 MaxValue 或小於 MinValuevalue is greater than MaxValue or less than MinValue.

範例

下列Byte範例會將值轉換DoubleByte,並Double將值轉換為。The following example converts a Byte value to a Double and a Double value to a Byte.

public:
   void ConvertDoubleByte( double doubleVal )
   {
      Byte byteVal = 0;
      
      // Double to Byte conversion can overflow.
      try
      {
         byteVal = System::Convert::ToByte( doubleVal );
         System::Console::WriteLine( " {0} as a Byte is: {1}.",
         doubleVal, byteVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine( "Overflow in double-to-Byte conversion." );
      }
      
      // Byte to double conversion cannot overflow.
      doubleVal = System::Convert::ToDouble( byteVal );
      System::Console::WriteLine( " {0} as a double is: {1}.",
         byteVal, doubleVal );
   }
public void ConvertDoubleByte(double doubleVal) {
    byte	byteVal = 0;

    // Double to byte conversion can overflow.
    try {
        byteVal = System.Convert.ToByte(doubleVal);
        System.Console.WriteLine("{0} as a byte is: {1}.",
            doubleVal, byteVal);
    } 
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "Overflow in double-to-byte conversion.");
    }

    // Byte to double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(byteVal);
    System.Console.WriteLine("{0} as a double is: {1}.",
        byteVal, doubleVal);
}
Public Sub ConvertDoubleByte(ByVal doubleVal As Double)
    Dim byteVal As Byte = 0

    ' Double to Byte conversion can overflow.
    Try
        byteVal = System.Convert.ToByte(doubleVal)
        System.Console.WriteLine("{0} as a Byte is: {1}.", _
            doubleVal, byteVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in Double-to-Byte conversion.")
    End Try

    ' Byte to Double conversion cannot overflow.
    doubleVal = System.Convert.ToDouble(byteVal)
    System.Console.WriteLine("{0} as a Double is: {1}.", _
                              byteVal, doubleVal)
End Sub

ToByte(Int64)

將指定的 64 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 64-bit signed integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(long value);
public static byte ToByte (long value);
static member ToByte : int64 -> byte
Public Shared Function ToByte (value As Long) As Byte

參數

value
Int64

要轉換的 64 位元帶正負號的整數。The 64-bit signed integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

例外狀況

value 小於 MinValue 或大於 MaxValuevalue is less than MinValue or greater than MaxValue.

範例

下列範例會將值的Int64陣列轉換成Byte值。The following example converts an array of Int64 values to Byte values.

long[] numbers = { Int64.MinValue, -1, 0, 121, 340, Int64.MaxValue };
byte result;
foreach (long number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       The Int64 value -9223372036854775808 is outside the range of the Byte type.
//       The Int64 value -1 is outside the range of the Byte type.
//       Converted the Int64 value 0 to the Byte value 0.
//       Converted the Int64 value 121 to the Byte value 121.
//       The Int64 value 340 is outside the range of the Byte type.
//       The Int64 value 9223372036854775807 is outside the range of the Byte type.      
Dim numbers() As Long = { Int64.MinValue, -1, 0, 121, 340, Int64.MaxValue }
Dim result As Byte
For Each number As Long In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       The Int64 value -9223372036854775808 is outside the range of the Byte type.
'       The Int64 value -1 is outside the range of the Byte type.
'       Converted the Int64 value 0 to the Byte value 0.
'       Converted the Int64 value 121 to the Byte value 121.
'       The Int64 value 340 is outside the range of the Byte type.
'       The Int64 value 9223372036854775807 is outside the range of the Byte type.      

ToByte(Byte)

傳回指定的 8 位元不帶正負號整數;不會執行實際的轉換。Returns the specified 8-bit unsigned integer; no actual conversion is performed.

public:
 static System::Byte ToByte(System::Byte value);
public static byte ToByte (byte value);
static member ToByte : byte -> byte
Public Shared Function ToByte (value As Byte) As Byte

參數

value
Byte

要傳回之 8 位元不帶正負號的整數。The 8-bit unsigned integer to return.

傳回

value 會原封不動地傳回。value is returned unchanged.

ToByte(Char)

將指定的 Unicode 字元值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified Unicode character to the equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(char value);
public static byte ToByte (char value);
static member ToByte : char -> byte
Public Shared Function ToByte (value As Char) As Byte

參數

value
Char

要轉換的 Unicode 字元。The Unicode character to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

例外狀況

value 代表大於 MaxValue 的數字。value represents a number that is greater than MaxValue.

範例

下列範例會將值的Char陣列轉換成Byte值。The following example converts an array of Char values to Byte values.

char[] chars = { 'a', 'z', '\x0007', '\x03FF' };
foreach (char ch in chars)
{
   try {
      byte result = Convert.ToByte(ch);
      Console.WriteLine("{0} is converted to {1}.", ch, result);
   }   
   catch (OverflowException) {
      Console.WriteLine("Unable to convert u+{0} to a byte.", 
                        Convert.ToInt16(ch).ToString("X4"));
   }
}   
// The example displays the following output:
//       a is converted to 97.
//       z is converted to 122.
//        is converted to 7.
//       Unable to convert u+03FF to a byte.      
Dim chars() As Char = { "a"c, "z"c, ChrW(7), ChrW(1023) }
For Each ch As Char in chars
   Try
      Dim result As Byte = Convert.ToByte(ch)
      Console.WriteLine("{0} is converted to {1}.", ch, result)
   Catch e As OverflowException
      Console.WriteLIne("Unable to convert u+{0} to a byte.", _
                        AscW(ch).ToString("X4"))
   End Try
Next   
' The example displays the following output:
'       a is converted to 97.
'       z is converted to 122.
'        is converted to 7.
'       Unable to convert u+03FF to a byte.      

備註

這個方法會傳回不帶正負號的位元組值,表示傳遞Char給它的物件的數位代碼。This method returns an unsigned byte value that represents the numeric code of the Char object passed to it. 在 .NET Framework 中, Char物件是16位的值。In the .NET Framework, a Char object is a 16-bit value. 這表示方法適合用來傳回 ASCII 字元範圍或 Unicode C0 控制項中的字元數位代碼,以及從 U + 0000 到 U + 00FF 的 C1 控制項和拉丁-1 補充範圍。This means that the method is suitable for returning the numeric codes of characters in the ASCII character range or in the Unicode C0 Controls and Basic Latin, and C1 Controls and Latin-1 Supplement ranges, from U+0000 to U+00FF.

ToByte(DateTime)

呼叫這個方法一律會擲回 InvalidCastExceptionCalling this method always throws InvalidCastException.

public:
 static System::Byte ToByte(DateTime value);
public static byte ToByte (DateTime value);
static member ToByte : DateTime -> byte
Public Shared Function ToByte (value As DateTime) As Byte

參數

value
DateTime

要轉換的日期和時間值。The date and time value to convert.

傳回

不支援這個轉換。This conversion is not supported. 沒有傳回值。No value is returned.

例外狀況

不支援這個轉換。This conversion is not supported.

ToByte(Boolean)

將指定的布林值轉換為相等的 8 位元不帶正負號的整數。Converts the specified Boolean value to the equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(bool value);
public static byte ToByte (bool value);
static member ToByte : bool -> byte
Public Shared Function ToByte (value As Boolean) As Byte

參數

value
Boolean

要轉換的布林值。The Boolean value to convert.

傳回

如果 valuetrue,則為數字 1,否則為 0。The number 1 if value is true; otherwise, 0.

範例

下列範例說明Boolean如何將轉換成Byte值。The following example illustrates the conversion of Boolean to Byte values.

using namespace System;

void main()
{
   bool falseFlag = false;
   bool trueFlag = true;

   Console::WriteLine("{0} converts to {1}.", falseFlag,
                      Convert::ToByte(falseFlag));
   Console::WriteLine("{0} converts to {1}.", trueFlag, 
                      Convert::ToByte(trueFlag));
}
// The example displays the following output:
//       False converts to 0.
//       True converts to 1.
bool falseFlag = false;
bool trueFlag = true;

Console.WriteLine("{0} converts to {1}.", falseFlag, 
                  Convert.ToByte(falseFlag));
Console.WriteLine("{0} converts to {1}.", trueFlag, 
                  Convert.ToByte(trueFlag));
// The example displays the following output:
//       False converts to 0.
//       True converts to 1.
Dim falseFlag As Boolean = False
Dim trueFlag As Boolean = True

Console.WriteLine("{0} converts to {1}.", falseFlag, _
                  Convert.ToByte(falseFlag))
Console.WriteLine("{0} converts to {1}.", trueFlag, _
                  Convert.ToByte(trueFlag))
' The example displays the following output:
'       False converts to 0.
'       True converts to 1.

ToByte(Int16)

將指定的 16 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 16-bit signed integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(short value);
public static byte ToByte (short value);
static member ToByte : int16 -> byte
Public Shared Function ToByte (value As Short) As Byte

參數

value
Int16

要轉換的 16 位元帶正負號的整數。The 16-bit signed integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

例外狀況

value 小於 MinValue 或大於 MaxValuevalue is less than MinValue or greater than MaxValue.

範例

下列範例會將值的Int16陣列轉換成Byte值。The following example converts an array of Int16 values to Byte values.

short[] numbers = { Int16.MinValue, -1, 0, 121, 340, Int16.MaxValue };
byte result;
foreach (short number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       The Int16 value -32768 is outside the range of the Byte type.
//       The Int16 value -1 is outside the range of the Byte type.
//       Converted the Int16 value 0 to the Byte value 0.
//       Converted the Int16 value 121 to the Byte value 121.
//       The Int16 value 340 is outside the range of the Byte type.
//       The Int16 value 32767 is outside the range of the Byte type.
Dim numbers() As Short = { Int16.MinValue, -1, 0, 121, 340, Int16.MaxValue }
Dim result As Byte
For Each number As Short In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       The Int16 value -32768 is outside the range of the Byte type.
'       The Int16 value -1 is outside the range of the Byte type.
'       Converted the Int16 value 0 to the Byte value 0.
'       Converted the Int16 value 121 to the Byte value 121.
'       The Int16 value 340 is outside the range of the Byte type.
'       The Int16 value 32767 is outside the range of the Byte type.

ToByte(Int32)

將指定的 32 位元帶正負號的整數值轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified 32-bit signed integer to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(int value);
public static byte ToByte (int value);
static member ToByte : int -> byte
Public Shared Function ToByte (value As Integer) As Byte

參數

value
Int32

要轉換的 32 位元帶正負號的整數。The 32-bit signed integer to convert.

傳回

等於 value 的 8 位元不帶正負號整數。An 8-bit unsigned integer that is equivalent to value.

例外狀況

value 小於 MinValue 或大於 MaxValuevalue is less than MinValue or greater than MaxValue.

範例

下列範例會將值的Int32陣列轉換成Byte值。The following example converts an array of Int32 values to Byte values.

int[] numbers = { Int32.MinValue, -1, 0, 121, 340, Int32.MaxValue };
byte result;
foreach (int number in numbers)
{
   try {
      result = Convert.ToByte(number);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        number.GetType().Name, number, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException) {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        number.GetType().Name, number);
   }
}
// The example displays the following output:
//       The Int32 value -2147483648 is outside the range of the Byte type.
//       The Int32 value -1 is outside the range of the Byte type.
//       Converted the Int32 value 0 to the Byte value 0.
//       Converted the Int32 value 121 to the Byte value 121.
//       The Int32 value 340 is outside the range of the Byte type.
//       The Int32 value 2147483647 is outside the range of the Byte type.      
Dim numbers() As Integer = { Int32.MinValue, -1, 0, 121, 340, Int32.MaxValue }
Dim result As Byte
For Each number As Integer In numbers
   Try
      result = Convert.ToByte(number)
      Console.WriteLIne("Converted the {0} value {1} to the {2} value {3}.", _
                        number.GetType().Name, number, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        number.GetType().Name, number)
   End Try
Next
' The example displays the following output:
'       The Int32 value -2147483648 is outside the range of the Byte type.
'       The Int32 value -1 is outside the range of the Byte type.
'       Converted the Int32 value 0 to the Byte value 0.
'       Converted the Int32 value 121 to the Byte value 121.
'       The Int32 value 340 is outside the range of the Byte type.
'       The Int32 value 2147483647 is outside the range of the Byte type.      

ToByte(Decimal)

將指定之十進位數字的值,轉換為相等的 8 位元不帶正負號的整數。Converts the value of the specified decimal number to an equivalent 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::Decimal value);
public static byte ToByte (decimal value);
static member ToByte : decimal -> byte
Public Shared Function ToByte (value As Decimal) As Byte

參數

value
Decimal

要轉換的數字。The number to convert.

傳回

value,四捨五入為最接近的 8 位元不帶正負號整數。value, rounded to the nearest 8-bit unsigned integer. 如果 value 介於兩個整數正中間時,則傳回偶數;也就是 4.5 會轉換為 4,5.5 會轉換為 6。If value is halfway between two whole numbers, the even number is returned; that is, 4.5 is converted to 4, and 5.5 is converted to 6.

例外狀況

value 大於 MaxValue 或小於 MinValuevalue is greater than MaxValue or less than MinValue.

備註

下列Byte範例會將值轉換DecimalByte,並Decimal將值轉換為。The following example converts a Byte value to a Decimal and a Decimal value to a Byte.

public:
   void ConvertByteDecimal( Byte byteVal )
   {
      Decimal decimalVal;
      
      // Byte to decimal conversion will not overflow.
      decimalVal = System::Convert::ToDecimal( byteVal );
      System::Console::WriteLine( "The Byte as a decimal is {0}.",
         decimalVal );
      
      // Decimal to Byte conversion can overflow.
      try
      {
         byteVal = System::Convert::ToByte( decimalVal );
         System::Console::WriteLine( "The Decimal as a Byte is {0}.",
         byteVal );
      }
      catch ( System::OverflowException^ ) 
      {
         System::Console::WriteLine(
            "The decimal value is too large for a Byte." );
      }
   }
public void ConvertByteDecimal(byte byteVal) {
    decimal decimalVal;

    // Byte to decimal conversion will not overflow.
    decimalVal = System.Convert.ToDecimal(byteVal);
    System.Console.WriteLine("The byte as a decimal is {0}.",
        decimalVal);

    // Decimal to byte conversion can overflow.
    try {
        byteVal = System.Convert.ToByte(decimalVal);
        System.Console.WriteLine("The Decimal as a byte is {0}.",
            byteVal);
    }
    catch (System.OverflowException) {
        System.Console.WriteLine(
            "The decimal value is too large for a byte.");
    }
}
Public Sub ConvertByteDecimal(ByVal byteVal As Byte)
    Dim decimalVal As Decimal

    ' Byte to decimal conversion will not overflow.
    decimalVal = System.Convert.ToDecimal(byteVal)
    System.Console.WriteLine("The byte as a decimal is {0}.", _
                              decimalVal)

    ' Decimal to byte conversion can overflow.
    Try
        byteVal = System.Convert.ToByte(decimalVal)
        System.Console.WriteLine("The Decimal as a byte is {0}.", _
                                  byteVal)
    Catch exception As System.OverflowException
        System.Console.WriteLine( _
            "Overflow in decimal-to-byte conversion.")
    End Try
End Sub

ToByte(Object)

將指定之物件的值轉換為 8 位元不帶正負號的整數。Converts the value of the specified object to an 8-bit unsigned integer.

public:
 static System::Byte ToByte(System::Object ^ value);
public static byte ToByte (object value);
static member ToByte : obj -> byte
Public Shared Function ToByte (value As Object) As Byte

參數

value
Object

實作 IConvertible 介面的物件,或是 nullAn object that implements the IConvertible interface, or null.

傳回

8 位元不帶正負號的整數,等於 value;而若 valuenull,則為零。An 8-bit unsigned integer that is equivalent to value, or zero if value is null.

例外狀況

value 的屬性格式不適用於 Byte 值。value is not in the property format for a Byte value.

value 未實作 IConvertiblevalue does not implement IConvertible.

-或--or- 不支援從 value 轉換至 Byte 類型。Conversion from value to the Byte type is not supported.

value 代表小於 MinValue 或大於 MaxValue 的數字。value represents a number that is less than MinValue or greater than MaxValue.

範例

下列範例會使用ToByte(Object)方法,將物件的陣列轉換為Byte值。The following example uses the ToByte(Object) method to convert an array of objects to Byte values.

object[] values = { true, -12, 163, 935, 'x', "104", "103.0", "-1", 
                    "1.00e2", "One", 1.00e2};
byte result;
foreach (object value in values)
{
   try {
      result = Convert.ToByte(value);
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", 
                        value.GetType().Name, value, 
                        result.GetType().Name, result);
   }                     
   catch (OverflowException)
   {
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", 
                        value.GetType().Name, value);
   }                     
   catch (FormatException)
   {
      Console.WriteLine("The {0} value {1} is not in a recognizable format.", 
                        value.GetType().Name, value);
   }
   catch (InvalidCastException)
   {
      Console.WriteLine("No conversion to a Byte exists for the {0} value {1}.", 
                        value.GetType().Name, value);
                        
   }
}                           
// The example displays the following output:
//       Converted the Boolean value True to the Byte value 1.
//       The Int32 value -12 is outside the range of the Byte type.
//       Converted the Int32 value 163 to the Byte value 163.
//       The Int32 value 935 is outside the range of the Byte type.
//       Converted the Char value x to the Byte value 120.
//       Converted the String value 104 to the Byte value 104.
//       The String value 103.0 is not in a recognizable format.
//       The String value -1 is outside the range of the Byte type.
//       The String value 1.00e2 is not in a recognizable format.
//       The String value One is not in a recognizable format.
//       Converted the Double value 100 to the Byte value 100.      
Dim values() As Object = { True, -12, 163, 935, "x"c, "104", "103.0", "-1", _
                           "1.00e2", "One", 1.00e2}
Dim result As Byte
For Each value As Object In values
   Try
      result = Convert.ToByte(value)
      Console.WriteLine("Converted the {0} value {1} to the {2} value {3}.", _
                        value.GetType().Name, value, _
                        result.GetType().Name, result)
   Catch e As OverflowException
      Console.WriteLine("The {0} value {1} is outside the range of the Byte type.", _
                        value.GetType().Name, value)
   Catch e As FormatException
      Console.WriteLine("The {0} value {1} is not in a recognizable format.", _
                        value.GetType().Name, value)
   Catch e As InvalidCastException
      Console.WriteLine("No conversion to a Byte exists for the {0} value {1}.", _
                        value.GetType().Name, value)
                        
   End Try
Next                           
' The example displays the following output:
'       Converted the Boolean value True to the Byte value 1.
'       The Int32 value -12 is outside the range of the Byte type.
'       Converted the Int32 value 163 to the Byte value 163.
'       The Int32 value 935 is outside the range of the Byte type.
'       Converted the Char value x to the Byte value 120.
'       Converted the String value 104 to the Byte value 104.
'       The String value 103.0 is not in a recognizable format.
'       The String value -1 is outside the range of the Byte type.
'       The String value 1.00e2 is not in a recognizable format.
'       The String value One is not in a recognizable format.
'       Converted the Double value 100 to the Byte value 100.      

備註

如果value IConvertible.ToByte valuenull是,這個方法會包裝對的基礎類型之執行的呼叫。If value is not null, this method wraps a call to the IConvertible.ToByte implementation of the underlying type of value.

適用於