CharUnicodeInfo.GetNumericValue Method

Definition

Namespace:

System.Globalization

Assemblies:

netstandard.dll, System.Runtime.dll

Gets the numeric value associated with a Unicode character.

Overloads

GetNumericValue(Char)	Gets the numeric value associated with the specified character.
GetNumericValue(String, Int32)	Gets the numeric value associated with the character at the specified index of the specified string.

GetNumericValue(Char)

Source:

CharUnicodeInfo.cs

Gets the numeric value associated with the specified character.

C#

public static double GetNumericValue(char ch);

Parameters

ch

Char

The Unicode character for which to get the numeric value.

Returns

Double

The numeric value associated with the specified character.

-or-

-1, if the specified character is not a numeric character.

Examples

The following code example shows the values returned by each method for different types of characters.

C#

using System;
using System.Globalization;

public class SamplesCharUnicodeInfo  {

   public static void Main()  {

      Console.WriteLine( "                                        c  Num   Dig   Dec   UnicodeCategory" );

      Console.Write( "U+0061 LATIN SMALL LETTER A            " );
      PrintProperties( 'a' );

      Console.Write( "U+0393 GREEK CAPITAL LETTER GAMMA      " );
      PrintProperties( '\u0393' );

      Console.Write( "U+0039 DIGIT NINE                      " );
      PrintProperties( '9' );

      Console.Write( "U+00B2 SUPERSCRIPT TWO                 " );
      PrintProperties( '\u00B2' );

      Console.Write( "U+00BC VULGAR FRACTION ONE QUARTER     " );
      PrintProperties( '\u00BC' );

      Console.Write( "U+0BEF TAMIL DIGIT NINE                " );
      PrintProperties( '\u0BEF' );

      Console.Write( "U+0BF0 TAMIL NUMBER TEN                " );
      PrintProperties( '\u0BF0' );

      Console.Write( "U+0F33 TIBETAN DIGIT HALF ZERO         " );
      PrintProperties( '\u0F33' );

      Console.Write( "U+2788 CIRCLED SANS-SERIF DIGIT NINE   " );
      PrintProperties( '\u2788' );
   }

   public static void PrintProperties( char c )  {
      Console.Write( " {0,-3}", c );
      Console.Write( " {0,-5}", CharUnicodeInfo.GetNumericValue( c ) );
      Console.Write( " {0,-5}", CharUnicodeInfo.GetDigitValue( c ) );
      Console.Write( " {0,-5}", CharUnicodeInfo.GetDecimalDigitValue( c ) );
      Console.WriteLine( "{0}", CharUnicodeInfo.GetUnicodeCategory( c ) );
   }
}


/*
This code produces the following output.  Some characters might not display at the console.

                                        c  Num   Dig   Dec   UnicodeCategory
U+0061 LATIN SMALL LETTER A             a   -1    -1    -1   LowercaseLetter
U+0393 GREEK CAPITAL LETTER GAMMA       Γ   -1    -1    -1   UppercaseLetter
U+0039 DIGIT NINE                       9   9     9     9    DecimalDigitNumber
U+00B2 SUPERSCRIPT TWO                  ²   2     2     -1   OtherNumber
U+00BC VULGAR FRACTION ONE QUARTER      ¼   0.25  -1    -1   OtherNumber
U+0BEF TAMIL DIGIT NINE                 ௯   9     9     9    DecimalDigitNumber
U+0BF0 TAMIL NUMBER TEN                 ௰   10    -1    -1   OtherNumber
U+0F33 TIBETAN DIGIT HALF ZERO          ༳   -0.5  -1    -1   OtherNumber
U+2788 CIRCLED SANS-SERIF DIGIT NINE    ➈   9     9     -1   OtherNumber

*/

Remarks

Numeric value is a Unicode character property that applies only to numeric characters, which include fractions, subscripts, superscripts, Roman numerals, currency numerators, encircled numbers, and script-specific digits. For more information on Unicode characters, see the Unicode Standard.

The GetNumericValue(Char) method assumes that ch corresponds to a single linguistic character and checks whether that character can be converted to a decimal digit. However, some numbers in the Unicode standard are represented by two Char objects that form a surrogate pair. For example, the Aegean numbering system consists of code points U+10107 through U+10133. The following example uses the ConvertFromUtf32 method to instantiate a string that represents AEGEAN NUMBER ONE. As the output from the example shows, the GetNumericValue(Char) method returns -1 if it is passed either a high surrogate or a low surrogate of this character.

C#

int utf32 = 0x10107;       // AEGEAN NUMBER ONE
string surrogate = Char.ConvertFromUtf32(utf32);
foreach (var ch in surrogate)
   Console.WriteLine($"U+{(ushort)ch:X4}: {System.Globalization.CharUnicodeInfo.GetNumericValue(ch)}    ");

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

GetNumericValue(String, Int32)

Source:

CharUnicodeInfo.cs

Gets the numeric value associated with the character at the specified index of the specified string.

C#

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

Parameters

s

String

The String containing the Unicode character for which to get the numeric value.

index

Int32

The index of the Unicode character for which to get the numeric value.

Returns

Double

The numeric value associated with the character at the specified index of the specified string.

-or-

-1, if the character at the specified index of the specified string is not a numeric character.

Exceptions

ArgumentNullException

s is null.

ArgumentOutOfRangeException

index is outside the range of valid indexes in s.

Examples

The following code example shows the values returned by each method for different types of characters.

C#

using System;
using System.Globalization;

public class SamplesCharUnicodeInfo  {

   public static void Main()  {

      // The String to get information for.
      String s = "a9\u0393\u00B2\u00BC\u0BEF\u0BF0\u2788";
      Console.WriteLine( "String: {0}", s );

      // Print the values for each of the characters in the string.
      Console.WriteLine( "index c  Num   Dig   Dec   UnicodeCategory" );
      for ( int i = 0; i < s.Length; i++ )  {
         Console.Write( "{0,-5} {1,-3}", i, s[i] );
         Console.Write( " {0,-5}", CharUnicodeInfo.GetNumericValue( s, i ) );
         Console.Write( " {0,-5}", CharUnicodeInfo.GetDigitValue( s, i ) );
         Console.Write( " {0,-5}", CharUnicodeInfo.GetDecimalDigitValue( s, i ) );
         Console.WriteLine( "{0}", CharUnicodeInfo.GetUnicodeCategory( s, i ) );
      }
   }
}


/*
This code produces the following output.  Some characters might not display at the console.

String: a9Γ²¼௯௰➈
index c  Num   Dig   Dec   UnicodeCategory
0     a   -1    -1    -1   LowercaseLetter
1     9   9     9     9    DecimalDigitNumber
2     Γ   -1    -1    -1   UppercaseLetter
3     ²   2     2     -1   OtherNumber
4     ¼   0.25  -1    -1   OtherNumber
5     ௯   9     9     9    DecimalDigitNumber
6     ௰   10    -1    -1   OtherNumber
7     ➈   9     9     -1   OtherNumber

*/

Remarks

Numeric value is a Unicode character property that applies only to numeric characters, which include fractions, subscripts, superscripts, Roman numerals, currency numerators, encircled numbers, and script-specific digits. For more information on Unicode characters, see the Unicode Standard.

If the Char object at position index is the first character of a valid surrogate pair, the GetNumericValue(String, Int32) method determines whether the surrogate pair forms a numeric digit, and, if it does, returns its numeric value. For example, the Aegean numbering system consists of code points U+10107 through U+10133. The following example uses the ConvertFromUtf32 method to instantiate a string that represents each Aegean number. As the output from the example shows, the GetNumericValue(String, Int32) method returns the correct numeric value if it is passed the high surrogate of an Aegean number. However, if it is passed the low surrogate, it considers only the low surrogate in isolation and returns -1.

C#

// 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,
                    System.Globalization.CharUnicodeInfo.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