Export (0) Print
Expand All

Char.GetNumericValue Method (Char)

Updated: December 2010

Converts the specified numeric Unicode character to a double-precision floating point number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static double GetNumericValue(
	char c
)

Parameters

c
Type: System.Char

The Unicode character to convert.

Return Value

Type: System.Double
The numeric value of c if that character represents a number; otherwise, -1.0.

The c parameter must be the Char representation of a numeric value. For example, if c is "5", the return value is 5. However, if c is "z", the return value is -1.0.

A character has an associated numeric value if and only if it is a member of one of the following categories in UnicodeCategory: DecimalDigitNumber, LetterNumber, or OtherNumber.

The GetNumericValue method assumes that c 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 method returns false if it is passed either a high surrogate or a low surrogate of this character.

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

The following code example demonstrates GetNumericValue.

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"
	}
}

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

December 2010

Added information about how the method handles surrogate pairs.

Information enhancement.

Community Additions

ADD
Show:
© 2014 Microsoft