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Char.GetNumericValue Method (Char)

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 UnicodeCategory categories: 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(Char) method returns -1 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 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"
	}
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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