Char.GetNumericValue 方法

參考

定義

命名空間:: System

組件:: System.Runtime.dll

組件:: netstandard.dll

組件:: mscorlib.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

將指定的數字 Unicode 字元轉換成雙精確度浮點數。

多載

GetNumericValue(String, Int32)	將指定字串中指定位置的數字 Unicode 字元轉換成雙精確度浮點數。
GetNumericValue(Char)	將指定的數字 Unicode 字元轉換成雙精確度浮點數。

GetNumericValue(String, Int32)

將指定字串中指定位置的數字 Unicode 字元轉換成雙精確度浮點數。

public:
 static double GetNumericValue(System::String ^ s, int index);

public static double GetNumericValue (string s, int index);

static member GetNumericValue : string * int -> double

Public Shared Function GetNumericValue (s As String, index As Integer) As Double

參數

s: String

String。

index: Int32

s 中的字元位置。

傳回

Double

如果該字元代表一個數字，則為 index 中 s 位置處的字元數值，否則為 -1。

例外狀況

ArgumentNullException

s 為 null。

ArgumentOutOfRangeException

index 小於零或大於 s 中的最後一個位置。

範例

下列程式碼範例將示範 GetNumericValue 。

using namespace System;
int main()
{
   String^ str =  "input: 1";
   Console::WriteLine( Char::GetNumericValue( '8' ) ); // Output: "8"
   Console::WriteLine( Char::GetNumericValue( str, 7 ) ); // Output: "1"
}

using System;

public class GetNumericValueSample {
    public static void Main() {
        string str = "input: 1";

        Console.WriteLine(Char.GetNumericValue('8'));		// Output: "8"
        Console.WriteLine(Char.GetNumericValue(str, 7));	// Output: "1"
    }
}

open System

let str = "input: 1"

printfn $"{Char.GetNumericValue '8'}"       // Output: "8"
printfn $"{Char.GetNumericValue(str, 7)}"   // Output: "1"

Module GetNumericValueSample
    Sub Main()
        Dim str As String
        str = "input: 1"

        Console.WriteLine(Char.GetNumericValue("8"c))       ' Output: "8"
        Console.WriteLine(Char.GetNumericValue(str, 7))     ' Output: "1"
    End Sub
End Module

備註

s參數必須是數位值的字串表示。例如，如果位於位置的字元 index s 是 "5"，則傳回值為5。但是，如果位於位置的字元 index s 是 "z"，則傳回值為-1。

字串中的字元位置會從零開始編制索引。

只有當字元是下列其中一個類別的成員時，才會有相關聯的數值 UnicodeCategory ： DecimalDigitNumber 、 LetterNumber 或 OtherNumber 。

如果 Char 位於位置的物件 index 是有效代理組的第一個字元，則此 GetNumericValue(String, Int32) 方法會判斷代理組是否形成一個數位。例如，希臘愛琴大學編號系統是由程式碼點 U + 10107 至 U + 10133 所組成。下列範例 ConvertFromUtf32 會使用方法來具現化代表每個希臘愛琴大學號碼的字串。如範例的輸出所示， GetNumericValue(String, Int32) 如果將希臘愛琴大學數位的高代理傳遞給它，方法會傳回正確的數值。但是，如果將低代理傳遞給它，它只會考慮低代理的隔離，並傳回-1。

// Define a UTF32 value for each character in the
// Aegean numbering system.
for (int utf32 = 0x10107; utf32 <= 0x10133; utf32++) {
   string surrogate = Char.ConvertFromUtf32(utf32);
   for (int ctr = 0; ctr < surrogate.Length; ctr++)
      Console.Write("U+{0:X4} at position {1}: {2}     ",
                        Convert.ToUInt16(surrogate[ctr]), ctr,
                        Char.GetNumericValue(surrogate, ctr));

   Console.WriteLine();
}
// The example displays the following output:
//       U+D800 at position 0: 1     U+DD07 at position 1: -1
//       U+D800 at position 0: 2     U+DD08 at position 1: -1
//       U+D800 at position 0: 3     U+DD09 at position 1: -1
//       U+D800 at position 0: 4     U+DD0A at position 1: -1
//       U+D800 at position 0: 5     U+DD0B at position 1: -1
//       U+D800 at position 0: 6     U+DD0C at position 1: -1
//       U+D800 at position 0: 7     U+DD0D at position 1: -1
//       U+D800 at position 0: 8     U+DD0E at position 1: -1
//       U+D800 at position 0: 9     U+DD0F at position 1: -1
//       U+D800 at position 0: 10     U+DD10 at position 1: -1
//       U+D800 at position 0: 20     U+DD11 at position 1: -1
//       U+D800 at position 0: 30     U+DD12 at position 1: -1
//       U+D800 at position 0: 40     U+DD13 at position 1: -1
//       U+D800 at position 0: 50     U+DD14 at position 1: -1
//       U+D800 at position 0: 60     U+DD15 at position 1: -1
//       U+D800 at position 0: 70     U+DD16 at position 1: -1
//       U+D800 at position 0: 80     U+DD17 at position 1: -1
//       U+D800 at position 0: 90     U+DD18 at position 1: -1
//       U+D800 at position 0: 100     U+DD19 at position 1: -1
//       U+D800 at position 0: 200     U+DD1A at position 1: -1
//       U+D800 at position 0: 300     U+DD1B at position 1: -1
//       U+D800 at position 0: 400     U+DD1C at position 1: -1
//       U+D800 at position 0: 500     U+DD1D at position 1: -1
//       U+D800 at position 0: 600     U+DD1E at position 1: -1
//       U+D800 at position 0: 700     U+DD1F at position 1: -1
//       U+D800 at position 0: 800     U+DD20 at position 1: -1
//       U+D800 at position 0: 900     U+DD21 at position 1: -1
//       U+D800 at position 0: 1000     U+DD22 at position 1: -1
//       U+D800 at position 0: 2000     U+DD23 at position 1: -1
//       U+D800 at position 0: 3000     U+DD24 at position 1: -1
//       U+D800 at position 0: 4000     U+DD25 at position 1: -1
//       U+D800 at position 0: 5000     U+DD26 at position 1: -1
//       U+D800 at position 0: 6000     U+DD27 at position 1: -1
//       U+D800 at position 0: 7000     U+DD28 at position 1: -1
//       U+D800 at position 0: 8000     U+DD29 at position 1: -1
//       U+D800 at position 0: 9000     U+DD2A at position 1: -1
//       U+D800 at position 0: 10000     U+DD2B at position 1: -1
//       U+D800 at position 0: 20000     U+DD2C at position 1: -1
//       U+D800 at position 0: 30000     U+DD2D at position 1: -1
//       U+D800 at position 0: 40000     U+DD2E at position 1: -1
//       U+D800 at position 0: 50000     U+DD2F at position 1: -1
//       U+D800 at position 0: 60000     U+DD30 at position 1: -1
//       U+D800 at position 0: 70000     U+DD31 at position 1: -1
//       U+D800 at position 0: 80000     U+DD32 at position 1: -1
//       U+D800 at position 0: 90000     U+DD33 at position 1: -1

// Define a UTF32 value for each character in the
// Aegean numbering system.
for utf32 in 0x10107..0x10133 do
    let surrogate = Char.ConvertFromUtf32 utf32
    for i = 0 to surrogate.Length - 1 do
        printf $"U+{Convert.ToUInt16 surrogate[i]:X4} at position {i}: {Char.GetNumericValue(surrogate, i)}     "
    printfn ""

// The example displays the following output:
//       U+D800 at position 0: 1     U+DD07 at position 1: -1
//       U+D800 at position 0: 2     U+DD08 at position 1: -1
//       U+D800 at position 0: 3     U+DD09 at position 1: -1
//       U+D800 at position 0: 4     U+DD0A at position 1: -1
//       U+D800 at position 0: 5     U+DD0B at position 1: -1
//       U+D800 at position 0: 6     U+DD0C at position 1: -1
//       U+D800 at position 0: 7     U+DD0D at position 1: -1
//       U+D800 at position 0: 8     U+DD0E at position 1: -1
//       U+D800 at position 0: 9     U+DD0F at position 1: -1
//       U+D800 at position 0: 10     U+DD10 at position 1: -1
//       U+D800 at position 0: 20     U+DD11 at position 1: -1
//       U+D800 at position 0: 30     U+DD12 at position 1: -1
//       U+D800 at position 0: 40     U+DD13 at position 1: -1
//       U+D800 at position 0: 50     U+DD14 at position 1: -1
//       U+D800 at position 0: 60     U+DD15 at position 1: -1
//       U+D800 at position 0: 70     U+DD16 at position 1: -1
//       U+D800 at position 0: 80     U+DD17 at position 1: -1
//       U+D800 at position 0: 90     U+DD18 at position 1: -1
//       U+D800 at position 0: 100     U+DD19 at position 1: -1
//       U+D800 at position 0: 200     U+DD1A at position 1: -1
//       U+D800 at position 0: 300     U+DD1B at position 1: -1
//       U+D800 at position 0: 400     U+DD1C at position 1: -1
//       U+D800 at position 0: 500     U+DD1D at position 1: -1
//       U+D800 at position 0: 600     U+DD1E at position 1: -1
//       U+D800 at position 0: 700     U+DD1F at position 1: -1
//       U+D800 at position 0: 800     U+DD20 at position 1: -1
//       U+D800 at position 0: 900     U+DD21 at position 1: -1
//       U+D800 at position 0: 1000     U+DD22 at position 1: -1
//       U+D800 at position 0: 2000     U+DD23 at position 1: -1
//       U+D800 at position 0: 3000     U+DD24 at position 1: -1
//       U+D800 at position 0: 4000     U+DD25 at position 1: -1
//       U+D800 at position 0: 5000     U+DD26 at position 1: -1
//       U+D800 at position 0: 6000     U+DD27 at position 1: -1
//       U+D800 at position 0: 7000     U+DD28 at position 1: -1
//       U+D800 at position 0: 8000     U+DD29 at position 1: -1
//       U+D800 at position 0: 9000     U+DD2A at position 1: -1
//       U+D800 at position 0: 10000     U+DD2B at position 1: -1
//       U+D800 at position 0: 20000     U+DD2C at position 1: -1
//       U+D800 at position 0: 30000     U+DD2D at position 1: -1
//       U+D800 at position 0: 40000     U+DD2E at position 1: -1
//       U+D800 at position 0: 50000     U+DD2F at position 1: -1
//       U+D800 at position 0: 60000     U+DD30 at position 1: -1
//       U+D800 at position 0: 70000     U+DD31 at position 1: -1
//       U+D800 at position 0: 80000     U+DD32 at position 1: -1
//       U+D800 at position 0: 90000     U+DD33 at position 1: -1

' Define a UTF32 value for each character in the 
' Aegean numbering system.
For utf32 As Integer = &h10107 To &h10133
   Dim surrogate As String = Char.ConvertFromUtf32(utf32)
   For ctr As Integer = 0 To surrogate.Length - 1
      Console.Write("U+{0:X4} at position {1}: {2}     ", 
                        Convert.ToUInt16(surrogate(ctr)), ctr,  
                        Char.GetNumericValue(surrogate, ctr))
   Next
   Console.WriteLine()
Next    
' The example displays the following output:
'       U+D800 at position 0: 1     U+DD07 at position 1: -1
'       U+D800 at position 0: 2     U+DD08 at position 1: -1
'       U+D800 at position 0: 3     U+DD09 at position 1: -1
'       U+D800 at position 0: 4     U+DD0A at position 1: -1
'       U+D800 at position 0: 5     U+DD0B at position 1: -1
'       U+D800 at position 0: 6     U+DD0C at position 1: -1
'       U+D800 at position 0: 7     U+DD0D at position 1: -1
'       U+D800 at position 0: 8     U+DD0E at position 1: -1
'       U+D800 at position 0: 9     U+DD0F at position 1: -1
'       U+D800 at position 0: 10     U+DD10 at position 1: -1
'       U+D800 at position 0: 20     U+DD11 at position 1: -1
'       U+D800 at position 0: 30     U+DD12 at position 1: -1
'       U+D800 at position 0: 40     U+DD13 at position 1: -1
'       U+D800 at position 0: 50     U+DD14 at position 1: -1
'       U+D800 at position 0: 60     U+DD15 at position 1: -1
'       U+D800 at position 0: 70     U+DD16 at position 1: -1
'       U+D800 at position 0: 80     U+DD17 at position 1: -1
'       U+D800 at position 0: 90     U+DD18 at position 1: -1
'       U+D800 at position 0: 100     U+DD19 at position 1: -1
'       U+D800 at position 0: 200     U+DD1A at position 1: -1
'       U+D800 at position 0: 300     U+DD1B at position 1: -1
'       U+D800 at position 0: 400     U+DD1C at position 1: -1
'       U+D800 at position 0: 500     U+DD1D at position 1: -1
'       U+D800 at position 0: 600     U+DD1E at position 1: -1
'       U+D800 at position 0: 700     U+DD1F at position 1: -1
'       U+D800 at position 0: 800     U+DD20 at position 1: -1
'       U+D800 at position 0: 900     U+DD21 at position 1: -1
'       U+D800 at position 0: 1000     U+DD22 at position 1: -1
'       U+D800 at position 0: 2000     U+DD23 at position 1: -1
'       U+D800 at position 0: 3000     U+DD24 at position 1: -1
'       U+D800 at position 0: 4000     U+DD25 at position 1: -1
'       U+D800 at position 0: 5000     U+DD26 at position 1: -1
'       U+D800 at position 0: 6000     U+DD27 at position 1: -1
'       U+D800 at position 0: 7000     U+DD28 at position 1: -1
'       U+D800 at position 0: 8000     U+DD29 at position 1: -1
'       U+D800 at position 0: 9000     U+DD2A at position 1: -1
'       U+D800 at position 0: 10000     U+DD2B at position 1: -1
'       U+D800 at position 0: 20000     U+DD2C at position 1: -1
'       U+D800 at position 0: 30000     U+DD2D at position 1: -1
'       U+D800 at position 0: 40000     U+DD2E at position 1: -1
'       U+D800 at position 0: 50000     U+DD2F at position 1: -1
'       U+D800 at position 0: 60000     U+DD30 at position 1: -1
'       U+D800 at position 0: 70000     U+DD31 at position 1: -1
'       U+D800 at position 0: 80000     U+DD32 at position 1: -1
'       U+D800 at position 0: 90000     U+DD33 at position 1: -1

適用於

GetNumericValue(Char)

將指定的數字 Unicode 字元轉換成雙精確度浮點數。

public:
 static double GetNumericValue(char c);

public static double GetNumericValue (char c);

static member GetNumericValue : char -> double

Public Shared Function GetNumericValue (c As Char) As Double

參數

c: Char

要轉換的 Unicode 字元。

傳回

Double

如果該字元代表一個數字，則為 c 的數值，否則為 -1.0。

範例

下列範例將示範 GetNumericValue 。

using namespace System;
int main()
{
   String^ str =  "input: 1";
   Console::WriteLine( Char::GetNumericValue( '8' ) ); // Output: "8"
   Console::WriteLine( Char::GetNumericValue( str, 7 ) ); // Output: "1"
}

using System;

public class GetNumericValueSample {
    public static void Main() {
        string str = "input: 1";

        Console.WriteLine(Char.GetNumericValue('8'));		// Output: "8"
        Console.WriteLine(Char.GetNumericValue(str, 7));	// Output: "1"
    }
}

open System

let str = "input: 1"

printfn $"{Char.GetNumericValue '8'}"       // Output: "8"
printfn $"{Char.GetNumericValue(str, 7)}"   // Output: "1"

Module GetNumericValueSample
    Sub Main()
        Dim str As String
        str = "input: 1"

        Console.WriteLine(Char.GetNumericValue("8"c))       ' Output: "8"
        Console.WriteLine(Char.GetNumericValue(str, 7))     ' Output: "1"
    End Sub
End Module

備註

c參數必須是數值的 Char 標記法。例如，如果 c 是 "5"，則傳回值為5。但是，如果 c 是 "z"，則傳回值為-1.0。

只有當字元是下列其中一個類別的成員時，才會有相關聯的數值 UnicodeCategory ： DecimalDigitNumber 、 LetterNumber 或 OtherNumber 。

GetNumericValue方法假設 c 對應到單一語言字元，並檢查該字元是否可以轉換成十進位數。不過，Unicode 標準中的某些數位是由構成代理組的兩個物件所表示 Char 。例如，希臘愛琴大學編號系統是由程式碼點 U + 10107 至 U + 10133 所組成。下列範例 ConvertFromUtf32 會使用方法來具現化代表希臘愛琴大學數位1的字串。如範例的輸出所示， GetNumericValue(Char) 如果傳遞了高代理或此字元的低代理，則方法會傳回-1。

int utf32 = 0x10107;       // AEGEAN NUMBER ONE
string surrogate = Char.ConvertFromUtf32(utf32);
foreach (var ch in surrogate)
   Console.WriteLine("U+{0:X4}: {1}    ", Convert.ToUInt16(ch),
                                          Char.GetNumericValue(ch));

// The example displays the following output:
//       U+D800: -1
//       U+DD07: -1

let utf32 = 0x10107       // AEGEAN NUMBER ONE
let surrogate = Char.ConvertFromUtf32 utf32
for ch in surrogate do
    printfn $"U+{Convert.ToUInt16 ch:X4}: {Char.GetNumericValue ch}    "

// The example displays the following output:
//       U+D800: -1
//       U+DD07: -1

Dim utf32 As Integer = &h10107       ' AEGEAN NUMBER ONE
Dim surrogate As String = Char.ConvertFromUtf32(utf32)
For Each ch In surrogate
   Console.WriteLine("U+{0:X4}: {1}    ", Convert.ToUInt16(ch), 
                                          Char.GetNumericValue(ch))
Next
' The example displays the following output:
'       U+D800: -1
'       U+DD07: -1

另請參閱

GetNumericValue(Rune)

適用於

共用方式為

Char.GetNumericValue 方法

定義

多載

GetNumericValue(String, Int32)

參數

傳回

例外狀況

範例

備註

適用於

GetNumericValue(Char)

參數

傳回

範例

備註

另請參閱

適用於

其他資源