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 tp://go.microsoft.com/fwlink/?linkid=37123.

The CharUnicodeInfo.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 char.ConvertFromUtf32(int) method to instantiate a string that represents AEGEAN NUMBER ONE. As the output from the example shows, the CharUnicodeInfo.GetNumericValue(char) method returns -1 if it is passed either a high surrogate or a low surrogate of this character.

code reference: System.Globalization.CharUnicodeInfo.GetNumericValue#2

Namespace: System.Globalization
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0
Since: .NET 2.0